Web Animations CSS: Fix crash when transitioning background or mask properties

Source/core/rendering/style/StyleRareNonInheritedData.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 21 matching lines @@
 
 StyleRareNonInheritedData::StyleRareNonInheritedData()
     : opacity(RenderStyle::initialOpacity())
     , m_aspectRatioDenominator(RenderStyle::initialAspectRatioDenominator())
     , m_aspectRatioNumerator(RenderStyle::initialAspectRatioNumerator())
     , m_perspective(RenderStyle::initialPerspective())
     , m_perspectiveOriginX(RenderStyle::initialPerspectiveOriginX())
     , m_perspectiveOriginY(RenderStyle::initialPerspectiveOriginY())
     , lineClamp(RenderStyle::initialLineClamp())
     , m_draggableRegionMode(DraggableRegionNone)
-    , m_mask(FillLayer(MaskFillLayer))
+    , m_mask(MaskFillLayer, true)
     , m_pageSize()
     , m_shapeInside(RenderStyle::initialShapeInside())
     , m_shapeOutside(RenderStyle::initialShapeOutside())
     , m_shapeMargin(RenderStyle::initialShapeMargin())
     , m_shapePadding(RenderStyle::initialShapePadding())
     , m_shapeImageThreshold(RenderStyle::initialShapeImageThreshold())
     , m_clipPath(RenderStyle::initialClipPath())
     , m_visitedLinkBackgroundColor(RenderStyle::initialBackgroundColor())
     , m_order(RenderStyle::initialOrder())
     , m_objectPosition(RenderStyle::initialObjectPosition())
@@ skipping 244 matching lines @@
         return false;
     return true;
 }
 
 bool StyleRareNonInheritedData::hasFilters() const
 {
     return m_filter.get() && !m_filter->m_operations.isEmpty();
 }
 
 } // namespace WebCore