Bug 1141926 - Check nsCaret visibility when NotifySelectionChanged. r=roc

layout/base/nsCaret.cpp

@@ -551,7 +551,7 @@ NS_IMETHODIMP
 nsCaret::NotifySelectionChanged(nsIDOMDocument *, nsISelection *aDomSel,
                                 int16_t aReason)
 {
-  if (aReason & nsISelectionListener::MOUSEUP_REASON)//this wont do
+  if ((aReason & nsISelectionListener::MOUSEUP_REASON) || !IsVisible())//this wont do
     return NS_OK;
 
   nsCOMPtr<nsISelection> domSel(do_QueryReferent(mDomSelectionWeak));