diff --git a/common/models/templates/src/priority-queue.ts b/common/models/templates/src/priority-queue.ts
index bb4945d573..6a1344fd89 100644
--- a/common/models/templates/src/priority-queue.ts
+++ b/common/models/templates/src/priority-queue.ts
@@ -46,7 +46,7 @@ export default class PriorityQueue<Type> {
     // https://en.wikipedia.org/wiki/Min-max_heap
     this.comparator = comparator;
 
-    this.heap = Array.from(initialEntries ?? []);
+    this.heap = (initialEntries ?? []).slice(0);
     this.heapify();
   }
 
@@ -228,6 +228,6 @@ export default class PriorityQueue<Type> {
    * they will almost certainly be unsorted.
    */
   toArray(): Type[] {
-    return Array.from(this.heap);
+    return this.heap.slice(0);
   }
 }
\ No newline at end of file
diff --git a/common/models/templates/test/test-priority-queue.js b/common/models/templates/test/test-priority-queue.js
index 5fdd0caa3d..0887a19d22 100644
--- a/common/models/templates/test/test-priority-queue.js
+++ b/common/models/templates/test/test-priority-queue.js
@@ -24,7 +24,7 @@ describe('Priority queue', function() {
 
   it('initializes well from pre-existing values', function() {
     let input = [1, 10, 2, 9, 3, 8, 4, 7, 5, 6];
-    let originalInput = Array.from(input);
+    let originalInput = input.slice(0);
     let queue = new PriorityQueue((a, b) => a - b, input);
 
     assert.deepEqual(input, originalInput);
diff --git a/common/web/lm-worker/build-polyfill-concatenator.js b/common/web/lm-worker/build-polyfill-concatenator.js
index 3b350eb55e..9dfb901130 100644
--- a/common/web/lm-worker/build-polyfill-concatenator.js
+++ b/common/web/lm-worker/build-polyfill-concatenator.js
@@ -81,8 +81,6 @@ let sourceFileSet = [
   loadPolyfill('src/polyfills/array.fill.js', 'src/polyfills/array.fill.js'),
   // Needed for Android / Chromium browser pre-45.
   loadPolyfill('src/polyfills/array.findIndex.js', 'src/polyfills/array.findIndex.js'),
-  // Needed for Android / Chromium browser pre-45.
-  loadPolyfill('src/polyfills/array.from.js', 'src/polyfills/array.from.js'),
   // Needed for Android / Chromium browser pre-47.
   loadPolyfill('src/polyfills/array.includes.js', 'src/polyfills/array.includes.js'),
   // For Object.values, for iteration over object-based associate arrays.
diff --git a/common/web/lm-worker/src/main/correction/classical-calculation.ts b/common/web/lm-worker/src/main/correction/classical-calculation.ts
index 50ddf93551..296476b098 100644
--- a/common/web/lm-worker/src/main/correction/classical-calculation.ts
+++ b/common/web/lm-worker/src/main/correction/classical-calculation.ts
@@ -69,11 +69,11 @@ export class ClassicalDistanceCalculation<TUnit = string, TInput extends EditTok
       this.resolvedDistances = Array(rowCount);
 
       for(let r = 0; r < rowCount; r++) {
-        this.resolvedDistances[r] = Array.from(other.resolvedDistances[r]);
+        this.resolvedDistances[r] = other.resolvedDistances[r].slice(0);
       }
 
-      this.inputSequence = Array.from(other.inputSequence);
-      this.matchSequence = Array.from(other.matchSequence);
+      this.inputSequence = other.inputSequence.slice(0);
+      this.matchSequence = other.matchSequence.slice(0);
       this.diagonalWidth = other.diagonalWidth;
     } else {
       this.resolvedDistances = [];
diff --git a/common/web/lm-worker/src/main/correction/distance-modeler.ts b/common/web/lm-worker/src/main/correction/distance-modeler.ts
index 109a9dd682..c9cc7730ae 100644
--- a/common/web/lm-worker/src/main/correction/distance-modeler.ts
+++ b/common/web/lm-worker/src/main/correction/distance-modeler.ts
@@ -143,7 +143,7 @@ export class SearchNode {
 
       // TODO:  transform.deleteRight currently not supported.
 
-      let inputPath = Array.from(this.priorInput);
+      let inputPath = this.priorInput.slice(0);
       inputPath.push(probMass);
       // Tokenize and iterate over input chars, adding them into the calc.
       for(let i=0; i < transform.insert.length; i++) {
diff --git a/common/web/lm-worker/src/polyfills/array.from.js b/common/web/lm-worker/src/polyfills/array.from.js
deleted file mode 100644
index dc70987b8c..0000000000
--- a/common/web/lm-worker/src/polyfills/array.from.js
+++ /dev/null
@@ -1,81 +0,0 @@
-// From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from
-// Any npm-based ones require use of `require`, which won't work for us.
-
-// Production steps of ECMA-262, Edition 6, 22.1.2.1
-if (!Array.from) {
-  Array.from = (function () {
-    var toStr = Object.prototype.toString;
-    var isCallable = function (fn) {
-      return typeof fn === 'function' || toStr.call(fn) === '[object Function]';
-    };
-    var toInteger = function (value) {
-      var number = Number(value);
-      if (isNaN(number)) { return 0; }
-      if (number === 0 || !isFinite(number)) { return number; }
-      return (number > 0 ? 1 : -1) * Math.floor(Math.abs(number));
-    };
-    var maxSafeInteger = Math.pow(2, 53) - 1;
-    var toLength = function (value) {
-      var len = toInteger(value);
-      return Math.min(Math.max(len, 0), maxSafeInteger);
-    };
-
-    // The length property of the from method is 1.
-    return function from(arrayLike/*, mapFn, thisArg */) {
-      // 1. Let C be the this value.
-      var C = this;
-
-      // 2. Let items be ToObject(arrayLike).
-      var items = Object(arrayLike);
-
-      // 3. ReturnIfAbrupt(items).
-      if (arrayLike == null) {
-        throw new TypeError('Array.from requires an array-like object - not null or undefined');
-      }
-
-      // 4. If mapfn is undefined, then let mapping be false.
-      var mapFn = arguments.length > 1 ? arguments[1] : void undefined;
-      var T;
-      if (typeof mapFn !== 'undefined') {
-        // 5. else
-        // 5. a If IsCallable(mapfn) is false, throw a TypeError exception.
-        if (!isCallable(mapFn)) {
-          throw new TypeError('Array.from: when provided, the second argument must be a function');
-        }
-
-        // 5. b. If thisArg was supplied, let T be thisArg; else let T be undefined.
-        if (arguments.length > 2) {
-          T = arguments[2];
-        }
-      }
-
-      // 10. Let lenValue be Get(items, "length").
-      // 11. Let len be ToLength(lenValue).
-      var len = toLength(items.length);
-
-      // 13. If IsConstructor(C) is true, then
-      // 13. a. Let A be the result of calling the [[Construct]] internal method 
-      // of C with an argument list containing the single item len.
-      // 14. a. Else, Let A be ArrayCreate(len).
-      var A = isCallable(C) ? Object(new C(len)) : new Array(len);
-
-      // 16. Let k be 0.
-      var k = 0;
-      // 17. Repeat, while k < len… (also steps a - h)
-      var kValue;
-      while (k < len) {
-        kValue = items[k];
-        if (mapFn) {
-          A[k] = typeof T === 'undefined' ? mapFn(kValue, k) : mapFn.call(T, kValue, k);
-        } else {
-          A[k] = kValue;
-        }
-        k += 1;
-      }
-      // 18. Let putStatus be Put(A, "length", len, true).
-      A.length = len;
-      // 20. Return A.
-      return A;
-    };
-  }());
-}
diff --git a/common/web/lm-worker/src/polyfills/symbol-es6.min.js b/common/web/lm-worker/src/polyfills/symbol-es6.min.js
index 411bfde7d5..67d87dc45e 100644
--- a/common/web/lm-worker/src/polyfills/symbol-es6.min.js
+++ b/common/web/lm-worker/src/polyfills/symbol-es6.min.js
@@ -1,2 +1,7 @@
 // From https://rousan.io/symbol-es6/, lightly modified to be worker-compatible for Android Lollipop.
-!function(global,factory){"use strict";"object"==typeof module&&"object"==typeof module.exports?module.exports=factory(global):factory(global)}("undefined"!=typeof window?window:(self?self:global),function(global){"use strict";var defineProperty=Object.defineProperty,defineProperties=Object.defineProperties,symbolHiddenCounter=0,globalSymbolRegistry=[],slice=Array.prototype.slice,ES6="object"==typeof global.ES6?global.ES6:global.ES6={},isArray=Array.isArray,objectToString=Object.prototype.toString,push=Array.prototype.push,emptyFunction=function(){},simpleFunction=function(arg){return arg},isCallable=function(fn){return"function"==typeof fn},Iterator=function(){},ArrayIterator=function(array,flag){this._array=array,this._flag=flag,this._nextIndex=0},StringIterator=function(string,flag){this._string=string,this._flag=flag,this._nextIndex=0},isObject=function(value){return null!==value&&("object"==typeof value||"function"==typeof value)},setupSymbolInternals=function(symbol,desc){return defineProperties(symbol,{_description:{value:desc},_isSymbol:{value:!0},_id:{value:symbolHiddenCounter++}}),symbol},appendArray=function(array1,array2){if("number"==typeof array1.length&&array1.length>=0&&"number"==typeof array2.length&&array2.length>=0){var length1=Math.floor(array1.length),length2=Math.floor(array2.length),i=0;for(array1.length=length1+length2;i<length2;++i)array2.hasOwnProperty(i)&&(array1[length1+i]=array2[i])}},simpleInheritance=function(child,parent){if("function"!=typeof child||"function"!=typeof parent)throw new TypeError("Child and Parent must be function type");child.prototype=Object.create(parent.prototype),child.prototype.constructor=child},Symbol=function Symbol(desc){if(desc=void 0===desc?"":String(desc),this instanceof Symbol)throw new TypeError("Symbol is not a constructor");return setupSymbolInternals(Object.create(Symbol.prototype),desc)};defineProperties(Symbol,{for:{value:function(key){key=String(key);for(var record,registryLength=globalSymbolRegistry.length,i=0;i<registryLength;++i)if((record=globalSymbolRegistry[i]).key===key)return record.symbol;return record={key:key,symbol:Symbol(key)},globalSymbolRegistry.push(record),record.symbol},writable:!0,configurable:!0},keyFor:{value:function(symbol){if(!ES6.isSymbol(symbol))throw new TypeError(String(symbol)+" is not a symbol");for(var record,registryLength=globalSymbolRegistry.length,i=0;i<registryLength;++i)if((record=globalSymbolRegistry[i]).symbol===symbol)return record.key},writable:!0,configurable:!0},hasInstance:{value:Symbol("Symbol.hasInstance")},isConcatSpreadable:{value:Symbol("Symbol.isConcatSpreadable")},iterator:{value:Symbol("Symbol.iterator")},toStringTag:{value:Symbol("Symbol.toStringTag")}}),Symbol.prototype.toString=function(){return"@@_____"+this._id+"_____"},Symbol.prototype.valueOf=function(){return this},defineProperty(Iterator.prototype,Symbol.iterator.toString(),{value:function(){return this},writable:!0,configurable:!0}),simpleInheritance(ArrayIterator,Iterator),simpleInheritance(StringIterator,Iterator),defineProperty(ArrayIterator.prototype,Symbol.toStringTag.toString(),{value:"Array Iterator",configurable:!0}),defineProperty(StringIterator.prototype,Symbol.toStringTag.toString(),{value:"String Iterator",configurable:!0}),ArrayIterator.prototype.next=function(){if(!(this instanceof ArrayIterator))throw new TypeError("Method Array Iterator.prototype.next called on incompatible receiver "+String(this));var nextValue;return-1===this._nextIndex?{done:!0,value:void 0}:"number"==typeof this._array.length&&this._array.length>=0&&this._nextIndex<Math.floor(this._array.length)?(1===this._flag?nextValue=[this._nextIndex,this._array[this._nextIndex]]:2===this._flag?nextValue=this._array[this._nextIndex]:3===this._flag&&(nextValue=this._nextIndex),this._nextIndex++,{done:!1,value:nextValue}):(this._nextIndex=-1,{done:!0,value:void 0})},StringIterator.prototype.next=function(){if(!(this instanceof StringIterator))throw new TypeError("Method String Iterator.prototype.next called on incompatible receiver "+String(this));var nextValue,stringObject=new String(this._string);return-1===this._nextIndex?{done:!0,value:void 0}:this._nextIndex<stringObject.length?(nextValue=stringObject[this._nextIndex],this._nextIndex++,{done:!1,value:nextValue}):(this._nextIndex=-1,{done:!0,value:void 0})};var SpreadOperatorImpl=function(target,thisArg){this._target=target,this._values=[],this._thisArg=thisArg};SpreadOperatorImpl.prototype.spread=function(){var self=this;return slice.call(arguments).forEach(function(iterable){ES6.forOf(iterable,function(value){self._values.push(value)})}),self},SpreadOperatorImpl.prototype.add=function(){var self=this;return slice.call(arguments).forEach(function(value){self._values.push(value)}),self},SpreadOperatorImpl.prototype.call=function(thisArg){if("function"!=typeof this._target)throw new TypeError("Target is not a function");return thisArg=arguments.length<=0?this._thisArg:thisArg,this._target.apply(thisArg,this._values)},SpreadOperatorImpl.prototype.new=function(){if("function"!=typeof this._target)throw new TypeError("Target is not a constructor");var temp,returnValue;return temp=Object.create(this._target.prototype),returnValue=this._target.apply(temp,this._values),isObject(returnValue)?returnValue:temp},SpreadOperatorImpl.prototype.array=function(){if(!isArray(this._target))throw new TypeError("Target is not a array");return push.apply(this._target,this._values),this._target};return defineProperties(ES6,{isSymbol:{value:function(symbol){return symbol instanceof Symbol&&function(symbol){return!0===symbol._isSymbol&&"number"==typeof symbol._id&&"string"==typeof symbol._description}(symbol)},writable:!0,configurable:!0},instanceOf:{value:function(object,constructor){if(!isObject(constructor))throw new TypeError("Right-hand side of 'instanceof' is not an object");var hasInstanceSymbolProp=constructor[Symbol.hasInstance];if(void 0===hasInstanceSymbolProp)return object instanceof constructor;if("function"!=typeof hasInstanceSymbolProp)throw new TypeError(typeof hasInstanceSymbolProp+" is not a function");return hasInstanceSymbolProp.call(constructor,object)},writable:!0,configurable:!0},forOf:{value:function(iterable,callback,thisArg){if(callback="function"!=typeof callback?emptyFunction:callback,"function"!=typeof iterable[Symbol.iterator])throw new TypeError("Iterable[Symbol.iterator] is not a function");var iterationResult,iterator=iterable[Symbol.iterator]();if("function"!=typeof iterator.next)throw new TypeError(".iterator.next is not a function");for(;;){if(iterationResult=iterator.next(),!isObject(iterationResult))throw new TypeError("Iterator result "+iterationResult+" is not an object");if(iterationResult.done)break;callback.call(thisArg,iterationResult.value)}},writable:!0,configurable:!0},spreadOperator:{value:function(target,thisArg){if("function"!=typeof target&&!isArray(target))throw new TypeError("Spread operator only supports on array and function objects at this moment");return new SpreadOperatorImpl(target,thisArg)},writable:!0,configurable:!0}}),defineProperty(global,"Symbol",{value:Symbol,writable:!0,configurable:!0}),defineProperty(Function.prototype,Symbol.hasInstance.toString(),{value:function(instance){return"function"==typeof this&&instance instanceof this}}),defineProperty(Array.prototype,"concat",{value:function(){if(void 0===this||null===this)throw new TypeError("Array.prototype.concat called on null or undefined");var self=Object(this),targets=slice.call(arguments),outputs=[];return targets.unshift(self),targets.forEach(function(target){isObject(target)?void 0!==target[Symbol.isConcatSpreadable]?target[Symbol.isConcatSpreadable]?appendArray(outputs,target):outputs.push(target):isArray(target)?appendArray(outputs,target):outputs.push(target):outputs.push(target)}),outputs},writable:!0,configurable:!0}),defineProperty(Object.prototype,"toString",{value:function(){return void 0===this||null===this?objectToString.call(this):"string"==typeof this[Symbol.toStringTag]?"[object "+this[Symbol.toStringTag]+"]":objectToString.call(this)},writable:!0,configurable:!0}),defineProperty(Array.prototype,Symbol.iterator.toString(),{value:function(){if(void 0===this||null===this)throw new TypeError("Cannot convert undefined or null to object");var self=Object(this);return new ArrayIterator(self,2)},writable:!0,configurable:!0}),defineProperty(Array,"from",{value:function(arrayLike,mapFn,thisArg){var constructor,length,outputs,i=0;if(constructor=isCallable(this)?this:Array,void 0===arrayLike||null===arrayLike)throw new TypeError("Cannot convert undefined or null to object");if(arrayLike=Object(arrayLike),void 0===mapFn)mapFn=simpleFunction;else if(!isCallable(mapFn))throw new TypeError(mapFn+" is not a function");if(void 0===arrayLike[Symbol.iterator]){if(!("number"==typeof arrayLike.length&&arrayLike.length>=0))return(outputs=new constructor(0)).length=0,outputs;for(length=Math.floor(arrayLike.length),(outputs=new constructor(length)).length=length;i<length;++i)outputs[i]=mapFn.call(thisArg,arrayLike[i])}else(outputs=new constructor).length=0,ES6.forOf(arrayLike,function(value){outputs.length++,outputs[outputs.length-1]=mapFn.call(thisArg,value)});return outputs},writable:!0,configurable:!0}),defineProperty(Array.prototype,"entries",{value:function(){if(void 0===this||null===this)throw new TypeError("Cannot convert undefined or null to object");var self=Object(this);return new ArrayIterator(self,1)},writable:!0,configurable:!0}),defineProperty(Array.prototype,"keys",{value:function(){if(void 0===this||null===this)throw new TypeError("Cannot convert undefined or null to object");var self=Object(this);return new ArrayIterator(self,3)},writable:!0,configurable:!0}),defineProperty(String.prototype,Symbol.iterator.toString(),{value:function(){if(void 0===this||null===this)throw new TypeError("String.prototype[Symbol.iterator] called on null or undefined");return new StringIterator(String(this),0)},writable:!0,configurable:!0}),ES6});
\ No newline at end of file
+// The contents do not selectively polyfill; we'd prefer to use native if an implementation already exists.
+if(!self.Symbol) {
+
+!function(global,factory){"use strict";"object"==typeof module&&"object"==typeof module.exports?module.exports=factory(global):factory(global)}("undefined"!=typeof window?window:(self?self:global),function(global){"use strict";var defineProperty=Object.defineProperty,defineProperties=Object.defineProperties,symbolHiddenCounter=0,globalSymbolRegistry=[],slice=Array.prototype.slice,ES6="object"==typeof global.ES6?global.ES6:global.ES6={},isArray=Array.isArray,objectToString=Object.prototype.toString,push=Array.prototype.push,emptyFunction=function(){},simpleFunction=function(arg){return arg},isCallable=function(fn){return"function"==typeof fn},Iterator=function(){},ArrayIterator=function(array,flag){this._array=array,this._flag=flag,this._nextIndex=0},StringIterator=function(string,flag){this._string=string,this._flag=flag,this._nextIndex=0},isObject=function(value){return null!==value&&("object"==typeof value||"function"==typeof value)},setupSymbolInternals=function(symbol,desc){return defineProperties(symbol,{_description:{value:desc},_isSymbol:{value:!0},_id:{value:symbolHiddenCounter++}}),symbol},appendArray=function(array1,array2){if("number"==typeof array1.length&&array1.length>=0&&"number"==typeof array2.length&&array2.length>=0){var length1=Math.floor(array1.length),length2=Math.floor(array2.length),i=0;for(array1.length=length1+length2;i<length2;++i)array2.hasOwnProperty(i)&&(array1[length1+i]=array2[i])}},simpleInheritance=function(child,parent){if("function"!=typeof child||"function"!=typeof parent)throw new TypeError("Child and Parent must be function type");child.prototype=Object.create(parent.prototype),child.prototype.constructor=child},Symbol=function Symbol(desc){if(desc=void 0===desc?"":String(desc),this instanceof Symbol)throw new TypeError("Symbol is not a constructor");return setupSymbolInternals(Object.create(Symbol.prototype),desc)};defineProperties(Symbol,{for:{value:function(key){key=String(key);for(var record,registryLength=globalSymbolRegistry.length,i=0;i<registryLength;++i)if((record=globalSymbolRegistry[i]).key===key)return record.symbol;return record={key:key,symbol:Symbol(key)},globalSymbolRegistry.push(record),record.symbol},writable:!0,configurable:!0},keyFor:{value:function(symbol){if(!ES6.isSymbol(symbol))throw new TypeError(String(symbol)+" is not a symbol");for(var record,registryLength=globalSymbolRegistry.length,i=0;i<registryLength;++i)if((record=globalSymbolRegistry[i]).symbol===symbol)return record.key},writable:!0,configurable:!0},hasInstance:{value:Symbol("Symbol.hasInstance")},isConcatSpreadable:{value:Symbol("Symbol.isConcatSpreadable")},iterator:{value:Symbol("Symbol.iterator")},toStringTag:{value:Symbol("Symbol.toStringTag")}}),Symbol.prototype.toString=function(){return"@@_____"+this._id+"_____"},Symbol.prototype.valueOf=function(){return this},defineProperty(Iterator.prototype,Symbol.iterator.toString(),{value:function(){return this},writable:!0,configurable:!0}),simpleInheritance(ArrayIterator,Iterator),simpleInheritance(StringIterator,Iterator),defineProperty(ArrayIterator.prototype,Symbol.toStringTag.toString(),{value:"Array Iterator",configurable:!0}),defineProperty(StringIterator.prototype,Symbol.toStringTag.toString(),{value:"String Iterator",configurable:!0}),ArrayIterator.prototype.next=function(){if(!(this instanceof ArrayIterator))throw new TypeError("Method Array Iterator.prototype.next called on incompatible receiver "+String(this));var nextValue;return-1===this._nextIndex?{done:!0,value:void 0}:"number"==typeof this._array.length&&this._array.length>=0&&this._nextIndex<Math.floor(this._array.length)?(1===this._flag?nextValue=[this._nextIndex,this._array[this._nextIndex]]:2===this._flag?nextValue=this._array[this._nextIndex]:3===this._flag&&(nextValue=this._nextIndex),this._nextIndex++,{done:!1,value:nextValue}):(this._nextIndex=-1,{done:!0,value:void 0})},StringIterator.prototype.next=function(){if(!(this instanceof StringIterator))throw new TypeError("Method String Iterator.prototype.next called on incompatible receiver "+String(this));var nextValue,stringObject=new String(this._string);return-1===this._nextIndex?{done:!0,value:void 0}:this._nextIndex<stringObject.length?(nextValue=stringObject[this._nextIndex],this._nextIndex++,{done:!1,value:nextValue}):(this._nextIndex=-1,{done:!0,value:void 0})};var SpreadOperatorImpl=function(target,thisArg){this._target=target,this._values=[],this._thisArg=thisArg};SpreadOperatorImpl.prototype.spread=function(){var self=this;return slice.call(arguments).forEach(function(iterable){ES6.forOf(iterable,function(value){self._values.push(value)})}),self},SpreadOperatorImpl.prototype.add=function(){var self=this;return slice.call(arguments).forEach(function(value){self._values.push(value)}),self},SpreadOperatorImpl.prototype.call=function(thisArg){if("function"!=typeof this._target)throw new TypeError("Target is not a function");return thisArg=arguments.length<=0?this._thisArg:thisArg,this._target.apply(thisArg,this._values)},SpreadOperatorImpl.prototype.new=function(){if("function"!=typeof this._target)throw new TypeError("Target is not a constructor");var temp,returnValue;return temp=Object.create(this._target.prototype),returnValue=this._target.apply(temp,this._values),isObject(returnValue)?returnValue:temp},SpreadOperatorImpl.prototype.array=function(){if(!isArray(this._target))throw new TypeError("Target is not a array");return push.apply(this._target,this._values),this._target};return defineProperties(ES6,{isSymbol:{value:function(symbol){return symbol instanceof Symbol&&function(symbol){return!0===symbol._isSymbol&&"number"==typeof symbol._id&&"string"==typeof symbol._description}(symbol)},writable:!0,configurable:!0},instanceOf:{value:function(object,constructor){if(!isObject(constructor))throw new TypeError("Right-hand side of 'instanceof' is not an object");var hasInstanceSymbolProp=constructor[Symbol.hasInstance];if(void 0===hasInstanceSymbolProp)return object instanceof constructor;if("function"!=typeof hasInstanceSymbolProp)throw new TypeError(typeof hasInstanceSymbolProp+" is not a function");return hasInstanceSymbolProp.call(constructor,object)},writable:!0,configurable:!0},forOf:{value:function(iterable,callback,thisArg){if(callback="function"!=typeof callback?emptyFunction:callback,"function"!=typeof iterable[Symbol.iterator])throw new TypeError("Iterable[Symbol.iterator] is not a function");var iterationResult,iterator=iterable[Symbol.iterator]();if("function"!=typeof iterator.next)throw new TypeError(".iterator.next is not a function");for(;;){if(iterationResult=iterator.next(),!isObject(iterationResult))throw new TypeError("Iterator result "+iterationResult+" is not an object");if(iterationResult.done)break;callback.call(thisArg,iterationResult.value)}},writable:!0,configurable:!0},spreadOperator:{value:function(target,thisArg){if("function"!=typeof target&&!isArray(target))throw new TypeError("Spread operator only supports on array and function objects at this moment");return new SpreadOperatorImpl(target,thisArg)},writable:!0,configurable:!0}}),defineProperty(global,"Symbol",{value:Symbol,writable:!0,configurable:!0}),defineProperty(Function.prototype,Symbol.hasInstance.toString(),{value:function(instance){return"function"==typeof this&&instance instanceof this}}),defineProperty(Array.prototype,"concat",{value:function(){if(void 0===this||null===this)throw new TypeError("Array.prototype.concat called on null or undefined");var self=Object(this),targets=slice.call(arguments),outputs=[];return targets.unshift(self),targets.forEach(function(target){isObject(target)?void 0!==target[Symbol.isConcatSpreadable]?target[Symbol.isConcatSpreadable]?appendArray(outputs,target):outputs.push(target):isArray(target)?appendArray(outputs,target):outputs.push(target):outputs.push(target)}),outputs},writable:!0,configurable:!0}),defineProperty(Object.prototype,"toString",{value:function(){return void 0===this||null===this?objectToString.call(this):"string"==typeof this[Symbol.toStringTag]?"[object "+this[Symbol.toStringTag]+"]":objectToString.call(this)},writable:!0,configurable:!0}),defineProperty(Array.prototype,Symbol.iterator.toString(),{value:function(){if(void 0===this||null===this)throw new TypeError("Cannot convert undefined or null to object");var self=Object(this);return new ArrayIterator(self,2)},writable:!0,configurable:!0}),defineProperty(Array,"from",{value:function(arrayLike,mapFn,thisArg){var constructor,length,outputs,i=0;if(constructor=isCallable(this)?this:Array,void 0===arrayLike||null===arrayLike)throw new TypeError("Cannot convert undefined or null to object");if(arrayLike=Object(arrayLike),void 0===mapFn)mapFn=simpleFunction;else if(!isCallable(mapFn))throw new TypeError(mapFn+" is not a function");if(void 0===arrayLike[Symbol.iterator]){if(!("number"==typeof arrayLike.length&&arrayLike.length>=0))return(outputs=new constructor(0)).length=0,outputs;for(length=Math.floor(arrayLike.length),(outputs=new constructor(length)).length=length;i<length;++i)outputs[i]=mapFn.call(thisArg,arrayLike[i])}else(outputs=new constructor).length=0,ES6.forOf(arrayLike,function(value){outputs.length++,outputs[outputs.length-1]=mapFn.call(thisArg,value)});return outputs},writable:!0,configurable:!0}),defineProperty(Array.prototype,"entries",{value:function(){if(void 0===this||null===this)throw new TypeError("Cannot convert undefined or null to object");var self=Object(this);return new ArrayIterator(self,1)},writable:!0,configurable:!0}),defineProperty(Array.prototype,"keys",{value:function(){if(void 0===this||null===this)throw new TypeError("Cannot convert undefined or null to object");var self=Object(this);return new ArrayIterator(self,3)},writable:!0,configurable:!0}),defineProperty(String.prototype,Symbol.iterator.toString(),{value:function(){if(void 0===this||null===this)throw new TypeError("String.prototype[Symbol.iterator] called on null or undefined");return new StringIterator(String(this),0)},writable:!0,configurable:!0}),ES6});
+
+}
\ No newline at end of file
diff --git a/common/web/lm-worker/src/test/cases/edit-distance/context-tracker.js b/common/web/lm-worker/src/test/cases/edit-distance/context-tracker.js
index 2498834963..5c9d4812b6 100644
--- a/common/web/lm-worker/src/test/cases/edit-distance/context-tracker.js
+++ b/common/web/lm-worker/src/test/cases/edit-distance/context-tracker.js
@@ -21,7 +21,7 @@ describe('ContextTracker', function() {
         insert: '',
         deleteLeft: 0
       }
-      let newContext = Array.from(existingContext);
+      let newContext = existingContext.slice(0);
       newContext.splice(0, 1);
       let rawTokens = ["apple", null, "a", null, "day", null, "keeps", null, "the", null, "doctor"];
 
@@ -37,7 +37,7 @@ describe('ContextTracker', function() {
         insert: 'r',
         deleteLeft: 0
       }
-      let newContext = Array.from(existingContext);
+      let newContext = existingContext.slice(0);
       newContext[newContext.length - 1] = 'doctor';
       let rawTokens = ["an", null, "apple", null, "a", null, "day", null, "keeps", null, "the", null, "doctor"];
 
@@ -53,7 +53,7 @@ describe('ContextTracker', function() {
         insert: ' ',
         deleteLeft: 0
       }
-      let newContext = Array.from(existingContext);
+      let newContext = existingContext.slice(0);
       newContext.push('');
       let rawTokens = ["an", null, "apple", null, "a", null, "day", null, "keeps", null, "the", null, "doctor", null, ""];
 
@@ -73,7 +73,7 @@ describe('ContextTracker', function() {
         insert: 'a',
         deleteLeft: 0
       }
-      let newContext = Array.from(existingContext);
+      let newContext = existingContext.slice(0);
       newContext.push('a'); // The incoming transform should produce a new token WITH TEXT.
       let rawTokens = ["'", null, "a"];
 
@@ -93,7 +93,7 @@ describe('ContextTracker', function() {
         insert: ' ',
         deleteLeft: 0
       }
-      let newContext = Array.from(existingContext);
+      let newContext = existingContext.slice(0);
       newContext.splice(0, 1);
       newContext.push('');
       let rawTokens = ["apple", null, "a", null, "day", null, "keeps", null, "the", null, "doctor", null, ""];