--- a/dom/inputmethod/forms.js
+++ b/dom/inputmethod/forms.js
@@ -1175,17 +1175,16 @@ function replaceSurroundingText(element,
     // Insert the text to be replaced with.
     editor.insertText(text);
   }
   return true;
 }
 
 let CompositionManager =  {
   _isStarted: false,
-  _text: '',
   _clauseAttrMap: {
     'raw-input':
       Ci.nsICompositionStringSynthesizer.ATTR_RAWINPUT,
     'selected-raw-text':
       Ci.nsICompositionStringSynthesizer.ATTR_SELECTEDRAWTEXT,
     'converted-text':
       Ci.nsICompositionStringSynthesizer.ATTR_CONVERTEDTEXT,
     'selected-converted-text':
@@ -1228,56 +1227,46 @@ let CompositionManager =  {
       clauseLens.push(len);
       clauseAttrs.push(Ci.nsICompositionStringSynthesizer.ATTR_RAWINPUT);
     }
 
     // Start composition if need to.
     if (!this._isStarted) {
       this._isStarted = true;
       domWindowUtils.sendCompositionEvent('compositionstart', '', '');
-      this._text = '';
     }
 
     // Update the composing text.
-    if (this._text !== text) {
-      this._text = text;
-      domWindowUtils.sendCompositionEvent('compositionupdate', text, '');
-    }
     let compositionString = domWindowUtils.createCompositionStringSynthesizer();
     compositionString.setString(text);
     for (var i = 0; i < clauseLens.length; i++) {
       compositionString.appendClause(clauseLens[i], clauseAttrs[i]);
     }
     if (cursor >= 0) {
       compositionString.setCaret(cursor, 0);
     }
     compositionString.dispatchEvent();
   },
 
   endComposition: function cm_endComposition(text) {
     if (!this._isStarted) {
       return;
     }
     // Update the composing text.
-    if (this._text !== text) {
-      domWindowUtils.sendCompositionEvent('compositionupdate', text, '');
-    }
     let compositionString = domWindowUtils.createCompositionStringSynthesizer();
     compositionString.setString(text);
     // Set the cursor position to |text.length| so that the text will be
     // committed before the cursor position.
     compositionString.setCaret(text.length, 0);
     compositionString.dispatchEvent();
     domWindowUtils.sendCompositionEvent('compositionend', text, '');
-    this._text = '';
     this._isStarted = false;
   },
 
   // Composition ends due to external actions.
   onCompositionEnd: function cm_onCompositionEnd() {
     if (!this._isStarted) {
       return;
     }
 
-    this._text = '';
     this._isStarted = false;
   }
 };