Make removing a transform not crash.

sky/engine/core/rendering/RenderBox.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 166 matching lines @@
     bool had3DTransform = has3DTransform();
 
     bool hadTransform = m_transform;
     if (localHasTransform != hadTransform) {
         if (localHasTransform)
             m_transform = adoptPtr(new TransformationMatrix);
         else
             m_transform.clear();
 
         // Layers with transforms act as clip rects roots, so clear the cached clip rects here.
-        layer()->clipper().clearClipRectsIncludingDescendants();
-    } else if (localHasTransform) {
+        if (layer())
+            layer()->clipper().clearClipRectsIncludingDescendants();
+    } else if (localHasTransform && layer()) {
         layer()->clipper().clearClipRectsIncludingDescendants(AbsoluteClipRects);
     }
 
     updateTransformationMatrix();
 
-    if (had3DTransform != has3DTransform())
+    if (layer() && had3DTransform != has3DTransform())
         layer()->dirty3DTransformedDescendantStatus();
 }
 
 // TODO(ojan): Inline this into styleDidChange,
 void RenderBox::updateFromStyle()
 {
     RenderStyle* styleToUse = style();
 
     setHasBoxDecorationBackground(hasBackground() || styleToUse->hasBorder() || styleToUse->boxShadow());
     setInline(styleToUse->isDisplayInlineType());
@@ skipping 2869 matching lines @@
 
 RenderBox::BoxDecorationData::BoxDecorationData(const RenderStyle& style)
 {
     backgroundColor = style.colorIncludingFallback(CSSPropertyBackgroundColor);
     hasBackground = backgroundColor.alpha() || style.hasBackgroundImage();
     ASSERT(hasBackground == style.hasBackground());
     hasBorder = style.hasBorder();
 }
 
 } // namespace blink