Bug 526286 - Detaching a tab by dragging it down into its content area stopped working, r=enndeakin, sr=jonas

--HG--
extra : rebase_source : 7b04c1dc00bb1e55eba73222d185b37cbbb125be

content/base/src/nsContentAreaDragDrop.cpp

@@ -328,24 +328,7 @@ nsContentAreaDragDrop::DragOver(nsIDOMDragEvent* inEvent)
     }
   }
 
-  nsCOMPtr<nsIDOMNSEvent> e = do_QueryInterface(inEvent);
-  NS_ENSURE_STATE(e);
-  nsCOMPtr<nsIDOMEventTarget> target;
-  e->GetOriginalTarget(getter_AddRefs(target));
-  nsCOMPtr<nsINode> node = do_QueryInterface(target);
-  if (!node) {
-    nsCOMPtr<nsPIDOMWindow> win = do_QueryInterface(target);
-    if (win) {
-      node = do_QueryInterface(win->GetExtantDocument());
-    }
-  }
-  PRBool isChrome =
-    node ? nsContentUtils::IsChromeDoc(node->GetOwnerDoc()) : PR_FALSE;
-  if (isChrome) {
-    session->SetCanDrop(dropAllowed);
-  } else if (dropAllowed) {
-    inEvent->PreventDefault();
-  }
+  session->SetCanDrop(dropAllowed);
 
   return NS_OK;
 }

content/events/src/nsEventStateManager.cpp

@@ -3133,7 +3133,8 @@ nsEventStateManager::PostHandleEvent(nsPresContext* aPresContext,
             !(aEvent->flags & NS_EVENT_FLAG_NO_DEFAULT_CALLED_IN_CONTENT));
         }
       } else if (aEvent->message == NS_DRAGDROP_OVER && !isChromeDoc) {
-        dragSession->SetCanDrop(PR_FALSE);
+        // No one called preventDefault(), so handle drop only in chrome.
+        dragSession->SetOnlyChromeDrop(PR_TRUE);
       }
 
       // now set the drop effect in the initial dataTransfer. This ensures