Recompute overflow after transform changes

Source/core/rendering/RenderObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 2094 matching lines @@
         if (diff == StyleDifferenceLayout)
             setNeedsLayoutAndPrefWidthsRecalc();
         else
             setNeedsSimplifiedNormalFlowLayout();
     } else if (diff == StyleDifferenceSimplifiedLayoutAndPositionedMovement) {
         setNeedsPositionedMovementLayout();
         setNeedsSimplifiedNormalFlowLayout();
     } else if (diff == StyleDifferenceLayoutPositionedMovementOnly)
         setNeedsPositionedMovementLayout();
 
+    if (!needsLayout() && oldStyle && oldStyle->transform() != m_style->transform()) {
+        if (RenderBlock* container = containingBlock())
+            container->updateOverflowForTransform();

[esprehn, 2014/03/26 02:06:20]

This needs to be async, otherwise if you transform a thousand things you
recompute this a thousand times.

+    }
+
     // Don't check for repaint here; we need to wait until the layer has been
     // updated by subclasses before we know if we have to repaint (in setStyle()).
 
     if (oldStyle && !areCursorsEqual(oldStyle, style())) {
         if (LocalFrame* frame = this->frame())
             frame->eventHandler().scheduleCursorUpdate();
     }
 }
 
 void RenderObject::propagateStyleToAnonymousChildren(bool blockChildrenOnly)
@@ skipping 1220 matching lines @@
 {
     if (object1) {
         const WebCore::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif