Add static root property tree nodes [spv2]

third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef TransformPaintPropertyNode_h
 #define TransformPaintPropertyNode_h
 
 #include "platform/PlatformExport.h"
 #include "platform/geometry/FloatPoint3D.h"
 #include "platform/transforms/TransformationMatrix.h"
@@ skipping 29 matching lines @@
         m_flattensInheritedTransform = flattensInheritedTransform;
         m_renderingContextID = renderingContextID;
     }
 
     const TransformationMatrix& matrix() const { return m_matrix; }
     const FloatPoint3D& origin() const { return m_origin; }
 
     // Parent transform that this transform is relative to, or nullptr if this
     // is the root transform.
     const TransformPaintPropertyNode* parent() const { return m_parent.get(); }
+    bool isRoot() const { return !m_parent; }
 
     // If true, content with this transform node (or its descendant) appears in
     // the plane of its parent. This is implemented by flattening the total
     // accumulated transform from its ancestors.
     bool flattensInheritedTransform() const { return m_flattensInheritedTransform; }
 
     // Content whose transform nodes have a common rendering context ID are 3D
     // sorted. If this is 0, content will not be 3D sorted.
     unsigned renderingContextID() const { return m_renderingContextID; }
     bool hasRenderingContext() const { return m_renderingContextID; }
@@ skipping 20 matching lines @@
     unsigned m_renderingContextID;
 };
 
 // Redeclared here to avoid ODR issues.
 // See platform/testing/PaintPrinters.h.
 void PrintTo(const TransformPaintPropertyNode&, std::ostream*);
 
 } // namespace blink
 
 #endif // TransformPaintPropertyNode_h