Use same layout logic in animations for deciding whether an element can transform

third_party/WebKit/Source/core/layout/LayoutObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. 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 694 matching lines @@
     bool selfNeedsOverflowRecalcAfterStyleChange() const { return m_bitfields.selfNeedsOverflowRecalcAfterStyleChange(); }
     bool childNeedsOverflowRecalcAfterStyleChange() const { return m_bitfields.childNeedsOverflowRecalcAfterStyleChange(); }
 
     bool isSelectionBorder() const;
 
     bool hasClip() const { return isOutOfFlowPositioned() && !style()->hasAutoClip(); }
     bool hasOverflowClip() const { return m_bitfields.hasOverflowClip(); }
     bool hasClipRelatedProperty() const { return hasClip() || hasOverflowClip() || style()->containsPaint(); }
 
     bool hasTransformRelatedProperty() const { return m_bitfields.hasTransformRelatedProperty(); }
+    bool canTransform() const { return isBox(); }

[trchen, 2016/08/09 01:22:02]

SVG? For example: http://codepen.io/chriscoyier/pen/dvjhn/
I think the condition in CompositorAnimations.cpp was written in the way to not
to exclude SVG.

According to the spec:
https://drafts.csswg.org/css-transforms/#transformable-element
For CSS box model elements it is essentially isBox(). I think the standard just
spec'd after WebKit.
I'm not familiar with SVGs though. I guess all LayoutSVGModelObject supports
transform?

     bool hasMask() const { return style() && style()->hasMask(); }
     bool hasClipPath() const { return style() && style()->clipPath(); }
     bool hasHiddenBackface() const { return style() && style()->backfaceVisibility() == BackfaceVisibilityHidden; }
     bool hasBackdropFilter() const { return style() && style()->hasBackdropFilter(); }
 
     // Returns |true| if any property that renders using filter operations is
     // used (including, but not limited to, 'filter').
     bool hasFilterInducingProperty() const
     {
         return (style() && style()->hasFilter()) || (RuntimeEnabledFeatures::cssBoxReflectFilterEnabled() && hasReflection());
@@ skipping 1456 matching lines @@
 void showTree(const blink::LayoutObject*);
 void showLineTree(const blink::LayoutObject*);
 void showLayoutTree(const blink::LayoutObject* object1);
 // We don't make object2 an optional parameter so that showLayoutTree
 // can be called from gdb easily.
 void showLayoutTree(const blink::LayoutObject* object1, const blink::LayoutObject* object2);
 
 #endif
 
 #endif // LayoutObject_h