Check subtree paint invalidation when overflow clip status changes

third_party/WebKit/Source/core/layout/LayoutBlock.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 227 matching lines @@
 }
 
 void LayoutBlock::updateFromStyle()
 {
     LayoutBox::updateFromStyle();
 
     bool shouldClipOverflow = !styleRef().isOverflowVisible() && allowsOverflowClip();
     if (shouldClipOverflow != hasOverflowClip()) {
         if (!shouldClipOverflow)
             getScrollableArea()->invalidateAllStickyConstraints();
-        for (LayoutObject* child = firstChild(); child; child = child->nextSibling())

[chrishtr, 2016/05/23 20:10:32]

Even before https://crrev.com/392652 it was a bug though, right? Just harder to
exhibit?

[Xianzhu, 2016/05/23 21:35:49]

I think so, but couldn't create a test case to fail before 392652.

-            child->setMayNeedPaintInvalidation();
+        setMayNeedPaintInvalidationSubtree();
     }
     setHasOverflowClip(shouldClipOverflow);
 }
 
 bool LayoutBlock::allowsOverflowClip() const
 {
     // If overflow has been propagated to the viewport, it has no effect here.
     return node() != document().viewportDefiningElement();
 }
 
@@ skipping 1655 matching lines @@
         for (TrackedLayoutBoxListHashSet::const_iterator it = positionedDescendantSet->begin(); it != end; ++it) {
             LayoutBox* currBox = *it;
             ASSERT(!currBox->needsLayout());
         }
     }
 }
 
 #endif
 
 } // namespace blink