Bug 681621 - Displayport is wrong after MozScrolledAreaChanged event when page is scrolled to the right [r=stechz]

mobile/chrome/content/bindings/browser.js

@@ -629,7 +629,7 @@ let ContentScroll =  {
         sendAsyncMessage("MozScrolledAreaChanged", {
           width: aEvent.width,
           height: aEvent.height,
-          left: aEvent.x
+          left: aEvent.x + content.scrollX
         });
 
         // Send event only after painting to make sure content views in the parent process have