Bug 676470, ensure null-checking mCurrentTarget actually works, r=masayuki

--HG--
extra : rebase_source : e07cf0b42b89ea8a9236e1519c4df43c31585bd6

dom/events/EventStateManager.cpp

@@ -481,32 +481,9 @@ EventStateManager::PreHandleEvent(nsPresContext* aPresContext,
   mCurrentTarget = aTargetFrame;
   mCurrentTargetContent = nullptr;
 
-  // Focus events don't necessarily need a frame.
-  if (NS_EVENT_NEEDS_FRAME(aEvent)) {
-    NS_ASSERTION(mCurrentTarget, "mCurrentTarget is null.  this should not happen.  see bug #13007");
-    if (!mCurrentTarget) return NS_ERROR_NULL_POINTER;
-  }
-#ifdef DEBUG
-  if (aEvent->HasDragEventMessage() && sIsPointerLocked) {
-    NS_ASSERTION(sIsPointerLocked,
-      "sIsPointerLocked is true. Drag events should be suppressed when the pointer is locked.");
-  }
-#endif
-  // Store last known screenPoint and clientPoint so pointer lock
-  // can use these values as constants.
-  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
-  if (aEvent->mFlags.mIsTrusted &&
-      ((mouseEvent && mouseEvent->IsReal()) ||
-       aEvent->mClass == eWheelEventClass) &&
-      !sIsPointerLocked) {
-    sLastScreenPoint =
-      UIEvent::CalculateScreenPoint(aPresContext, aEvent);
-    sLastClientPoint =
-      UIEvent::CalculateClientPoint(aPresContext, aEvent, nullptr);
-  }
-
   // Do not take account NS_MOUSE_ENTER/EXIT so that loading a page
   // when user is not active doesn't change the state to active.
+  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
   if (aEvent->mFlags.mIsTrusted &&
       ((mouseEvent && mouseEvent->IsReal() &&
         mouseEvent->message != NS_MOUSE_ENTER &&
@@ -524,10 +501,38 @@ EventStateManager::PreHandleEvent(nsPresContext* aPresContext,
     ++gMouseOrKeyboardEventCounter;
   }
 
-  *aStatus = nsEventStatus_eIgnore;
-
   WheelTransaction::OnEvent(aEvent);
 
+  // Focus events don't necessarily need a frame.
+  if (NS_EVENT_NEEDS_FRAME(aEvent)) {
+    NS_ASSERTION(mCurrentTarget,
+                 "mCurrentTarget is null.  this should not happen. "
+                 "see bug #13007");
+    if (!mCurrentTarget) {
+      return NS_ERROR_NULL_POINTER;
+    }
+  }
+#ifdef DEBUG
+  if (aEvent->HasDragEventMessage() && sIsPointerLocked) {
+    NS_ASSERTION(sIsPointerLocked,
+      "sIsPointerLocked is true. Drag events should be suppressed when "
+      "the pointer is locked.");
+  }
+#endif
+  // Store last known screenPoint and clientPoint so pointer lock
+  // can use these values as constants.
+  if (aEvent->mFlags.mIsTrusted &&
+      ((mouseEvent && mouseEvent->IsReal()) ||
+       aEvent->mClass == eWheelEventClass) &&
+      !sIsPointerLocked) {
+    sLastScreenPoint =
+      UIEvent::CalculateScreenPoint(aPresContext, aEvent);
+    sLastClientPoint =
+      UIEvent::CalculateClientPoint(aPresContext, aEvent, nullptr);
+  }
+
+  *aStatus = nsEventStatus_eIgnore;
+
   switch (aEvent->message) {
   case NS_CONTEXTMENU:
     if (sIsPointerLocked) {