RenderLayer::hasVisibleContent should ASSERT(!m_visibleContentStatusDirty)

Source/core/rendering/RenderLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 599 matching lines @@
         parent()->dirtyAncestorChainVisibleDescendantStatus();
 }
 
 void RenderLayer::dirtyVisibleContentStatus()
 {
     m_visibleContentStatusDirty = true;
     if (parent())
         parent()->dirtyAncestorChainVisibleDescendantStatus();
 }
 
+void RenderLayer::potentiallyDirtyVisibleContentStatus(EVisibility visibility)
+{
+    if (m_visibleContentStatusDirty)
+        return;
+    if (hasVisibleContent() == (visibility == VISIBLE))
+        return;
+    dirtyVisibleContentStatus();
+}
+
 void RenderLayer::dirtyAncestorChainVisibleDescendantStatus()
 {
     for (RenderLayer* layer = this; layer; layer = layer->parent()) {
         if (layer->m_visibleDescendantStatusDirty)
             break;
 
         layer->m_visibleDescendantStatusDirty = true;
     }
 }
 
@@ skipping 3119 matching lines @@
     }
 }
 
 void showLayerTree(const blink::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif