bug 511716 - trailing while panning fennec r=stuart

view/src/nsViewManager.cpp

@@ -581,8 +581,9 @@ NS_IMETHODIMP nsViewManager::Composite()
   if (!IsRootVM()) {
     return RootViewManager()->Composite();
   }
-  
+#ifndef MOZ_GFX_OPTIMIZE_MOBILE  
   if (UpdateCount() > 0)
+#endif
     {
       ForceUpdate();
       ClearUpdateCount();