Bug 676316 - Reverse the device motion listener removal early return logic. r=dougt

--HG--
extra : rebase_source : 026f0fe58b06fb3839826ba07ef4f9a2d89d1ef4

dom/system/nsDeviceMotion.cpp

@@ -209,7 +209,7 @@ NS_IMETHODIMP nsDeviceMotion::AddWindowListener(nsIDOMWindow *aWindow)
 
 NS_IMETHODIMP nsDeviceMotion::RemoveWindowListener(nsIDOMWindow *aWindow)
 {
-  if (mWindowListeners.IndexOf(aWindow) != NoIndex)
+  if (mWindowListeners.IndexOf(aWindow) == NoIndex)
     return NS_OK;
 
   mWindowListeners.RemoveElement(aWindow);