Ensure that we consistently check contains: paint for fixed position containment.

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

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * 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 461 matching lines @@
     void setRTLOrdering(Order o) { inherited_flags.m_rtlOrdering = o; }
 
     bool isStyleAvailable() const;
 
     bool hasAnyPublicPseudoStyles() const;
     bool hasPseudoStyle(PseudoId) const;
     void setHasPseudoStyle(PseudoId);
     bool hasUniquePseudoStyle() const;
     bool hasPseudoElementStyle() const;
 
+    // Note: canContainAbsolutePositionObjects should return true if canContainFixedPositionObjects.
+    // We currently never use this value directly, always OR'ing it with canContainFixedPositionObjects.
     bool canContainAbsolutePositionObjects() const { return position() != StaticPosition; }
     bool canContainFixedPositionObjects() const { return hasTransformRelatedProperty() || containsPaint();}
 
     // attribute getter methods
 
     EDisplay display() const { return static_cast<EDisplay>(noninherited_flags.effectiveDisplay); }
     EDisplay originalDisplay() const { return static_cast<EDisplay>(noninherited_flags.originalDisplay); }
 
     const Length& left() const { return surround->offset.left(); }
     const Length& right() const { return surround->offset.right(); }
@@ skipping 1555 matching lines @@
 }
 
 inline bool ComputedStyle::hasPseudoElementStyle() const
 {
     return noninherited_flags.pseudoBits & ElementPseudoIdMask;
 }
 
 } // namespace blink
 
 #endif // ComputedStyle_h