Implement SANACLAP (http://bit.ly/sanaclap).

third_party/WebKit/Source/core/style/ComputedStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2011 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 854 matching lines @@
                 || m_rareInheritedData->textStrokeColor() != other.m_rareInheritedData->textStrokeColor()
                 || m_rareInheritedData->textEmphasisColor() != other.m_rareInheritedData->textEmphasisColor()
                 || m_rareInheritedData->visitedLinkTextFillColor() != other.m_rareInheritedData->visitedLinkTextFillColor()
                 || m_rareInheritedData->visitedLinkTextStrokeColor() != other.m_rareInheritedData->visitedLinkTextStrokeColor()
                 || m_rareInheritedData->visitedLinkTextEmphasisColor() != other.m_rareInheritedData->visitedLinkTextEmphasisColor()
                 || m_rareInheritedData->textEmphasisFill != other.m_rareInheritedData->textEmphasisFill
                 || m_rareInheritedData->appliedTextDecorations != other.m_rareInheritedData->appliedTextDecorations)) {
                 diff.setTextDecorationOrColorChanged();
         }
     }
+
+    if (diff.needsLayout() || diff.transformChanged())

[ojan, 2016/08/16 23:54:32]

A couple thoughts on this.
1. You need to also check diff.needsPositionedMovementLayout.
2. Putting it in this function seems a bit strange to me. Maybe just put it
directly in visualInvalidationDiff?
3. I think this is fine for now for us to test it in the wild, but the thing we
spec/ship won't be able to use the needsLayout bit directly because it encodes
our current logic for what needs a layout, not something about which properties
changed. So, we probably need a TODO to that effect. For example:

-When opacity changes, we only set the needsLayout bit if the element changed
whether it was a stacking context, but probably want to always disable scroll
anchoring? Or do we?
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/style/Com....
-When the textAutoSizingMultiplier changes we set this bit, but probably
shouldn't disable scroll anchoring.

I'm sure there are other examples. I just found those as two quick ones staring
at the code.

Bugs/Sasha/Elliott: Do you have opinions on the best way to incorporate this
logic and/or whether we should always disable scroll anchoring on opacity
changes or just when stacking context state changes? I suspect Tab has opinions
on the latter too.

[Bugs Nash, 2016/08/17 02:08:46]

Isn't that already checked via diff.needsLayout()?
Agree it doesn't seem 'property specific' to me
Not sure. How does scroll anchoring currently decide what is a layout affecting
change? Should be the same no?

[skobes, 2016/08/17 18:50:32]

As bugsnash noted, needsLayout includes this.
Done.
Added TODO.  Agree the spec should reference specific properties and not our
needsLayout concept.  Implementation-wise I wonder if it's better to start with
needsLayout() and add exceptions for the cases where we set needsLayout but
don't want to disable anchoring.

+        diff.setLayoutAffectingPropertyChanged();
 }
 
 void ComputedStyle::addPaintImage(StyleImage* image)
 {
     if (!m_rareNonInheritedData.access()->m_paintImages)
         m_rareNonInheritedData.access()->m_paintImages = WTF::wrapUnique(new Vector<Persistent<StyleImage>>());
     m_rareNonInheritedData.access()->m_paintImages->append(image);
 }
 
 void ComputedStyle::addCursor(StyleImage* image, bool hotSpotSpecified, const IntPoint& hotSpot)
@@ skipping 1081 matching lines @@
         if (value < 0)
             fvalue -= 0.5f;
         else
             fvalue += 0.5f;
     }
 
     return roundForImpreciseConversion<int>(fvalue / zoomFactor);
 }
 
 } // namespace blink