Add a test for the default wordform to key function.

common/predictive-text/unit_tests/headless/worker-predict-trie.js

@@ -154,7 +154,36 @@ describe('LMLayerWorker trie model for word lists', function() {
         firstResults.map(s => s.displayAs)
       );
     });
-  })
+  });
+  
+  describe('The default key function', function () {
+    it('uses the default key function', function () {
+      var model = new TrieModel(jsonFixture('tries/accented'));
+
+      //   «nai|                » [Send]
+      //   [  ???  ] [  naïve  ] [  ???  ]
+      var [suggestion] = model.predict({
+        insert: 'i', deleteLeft: 0
+      }, {
+        left: 'na',
+        startOfBuffer: false,
+        endOfBuffer: true
+      }).map(getSample);
+      assert.strictEqual(suggestion.displayAs, 'naïve');
+
+      //   «Let‘s get some pho|       » [Send]
+      //   [  ???  ] [  phở  ] [  ???  ]
+      var [suggestion] = model.predict({
+        insert: 'o', deleteLeft: 0
+      }, {
+        left: 'Let‘s get some ph',
+        startOfBuffer: false,
+        endOfBuffer: true
+      }).map(getSample);
+      assert.strictEqual(suggestion.displayAs, 'phở');
+
+    });
+  });
 
   it('replaces the entire typed word when a suggestion is accepted', function () {
       // Ensure that all input is lower-cased when we try to look it up.

common/predictive-text/unit_tests/in_browser/json/tries/accented.json

@@ -0,0 +1 @@
+{"type":"internal","weight":1,"values":["p","n"],"children":{"p":{"type":"leaf","weight":1,"entries":[{"key":"pho","weight":1,"content":"phở"}]},"n":{"type":"leaf","weight":1,"entries":[{"key":"naive","weight":1,"content":"naïve"}]}}}

common/predictive-text/worker/models/trie-model.ts

@@ -429,7 +429,7 @@
    */
   function defaultWordform2Key(wordform: string): SearchKey {
     return wordform
-      .replace(/[\u0100-\u2200]/, function (c) {
+      .replace(/[\u0100-\u2200]/g, function (c) {
         if (c in PARTIAL_NFD_LOOKUP) {
           return PARTIAL_NFD_LOOKUP[c];
         }