Merge backout of 02384ea1b0d9 (bug 480860)

mobile/chrome/content/WidgetStack.js

@@ -720,12 +720,7 @@ WidgetStack.prototype = {
     this._viewingRect.width = width;
     this._viewingRect.height = height;
 
-    // Wrap this call in a batch to ensure that we always call the
-    // viewportUpdateHandler, even if _adjustViewingRect doesn't trigger a pan.
-    // If it does, the batch also ensures that we don't call the handler twice.
-    this.beginUpdateBatch();
     this._adjustViewingRect();
-    this.endUpdateBatch();
   },
 
   beginUpdateBatch: function startUpdate() {