Don't apply overflow clips in paint invalidation.

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. 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
@@ skipping 1007 matching lines @@
         result.intersect(clipRect(LayoutPoint()));
 
     return result;
 }
 
 bool LayoutBox::mapScrollingContentsRectToBoxSpace(LayoutRect& rect, ApplyOverflowClipFlag applyOverflowClip, VisualRectFlags visualRectFlags) const
 {
     if (!hasClipRelatedProperty())
         return true;
 
-    if (applyOverflowClip == ApplyNonScrollOverflowClip && scrollsOverflow())
+    if (applyOverflowClip == ApplyNonScrollOverflowClip)

[wkorman, 2016/08/26 22:58:03]

In reviewing the docs for this method to make sure we didn't need to update
them, I saw this:

https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/layout/La...

    // If edgeInclusive is true, then this method may return true even
    // if the resulting rect has zero area.

There is no sign of 'edgeInclusive' except in VisualRectFlags which is not a
part of this method. If this just a totally stale comment maybe remove as part
of this change.

[chrishtr, 2016/08/26 23:05:18]

See line 1041 in the new file.

[wkorman, 2016/08/27 00:32:02]

May have forgotten to add file or upload

         return true;
 
     if (hasOverflowClip()) {
         LayoutSize offset = LayoutSize(-scrolledContentOffset());
         rect.move(offset);
     }
 
     // This won't work fully correctly for fixed-position elements, who should receive CSS clip but for whom the current object
     // is not in the containing block chain.
     LayoutRect clipRect = clippingRect();
@@ skipping 3786 matching lines @@
         m_rareData->m_snapAreas->remove(&snapArea);
     }
 }
 
 SnapAreaSet* LayoutBox::snapAreas() const
 {
     return m_rareData ? m_rareData->m_snapAreas.get() : nullptr;
 }
 
 } // namespace blink