21723. a=chofmann, r=rpotts. Laying ground work for FTP checkin. This fixes an oppressive event queue api method. We weren't returning the event to be processed. subsequently the event was being lost. There are currently *no* users of this method in the tree.

xpcom/threads/nsEventQueue.cpp

@@ -239,14 +239,14 @@ nsEventQueueImpl::HandleEvent(PLEvent* aEvent)
 }
 
 NS_IMETHODIMP
-nsEventQueueImpl::WaitForEvent()
+nsEventQueueImpl::WaitForEvent(PLEvent** aResult)
 {
     PRBool correctThread = PL_IsQueueOnCurrentThread(mEventQueue);
     NS_ASSERTION(correctThread, "attemping to process events on the wrong thread");
     if (!correctThread)
       return NS_ERROR_FAILURE;
 
-    PL_WaitForEvent(mEventQueue);
+    *aResult = PL_WaitForEvent(mEventQueue);
     CheckForDeactivation();
     return NS_OK;
 }