Bug 747851 - Only fire change if a select changed. r=mfinkle

mobile/android/chrome/content/SelectHelper.js

@@ -28,6 +28,7 @@ var SelectHelper = {
     if (selected == -1)
         return;
 
+    var changed = false;
     if (aElement instanceof Ci.nsIDOMXULMenuListElement) {
       aElement.selectedIndex = selected;
     } else if (aElement instanceof HTMLSelectElement) {
@@ -40,10 +41,14 @@ var SelectHelper = {
       }
       let i = 0;
       this.forOptions(aElement, function(aNode) {
+        if (aNode.selected != selected[i])
+          changed = true;
         aNode.selected = selected[i++];
       });
     }
-    this.fireOnChange(aElement);
+
+    if (changed)
+      this.fireOnChange(aElement);
   },
 
   _isMenu: function(aElement) {