GeometryMapper: Support computing visual rects in spaces that are not direct ancestors.

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

Index: third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h
diff --git a/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h b/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h
index 0bef99ee629614eaf4044374528e81fd3c151030..03980087c1c8c198b83549a2574fbd84142fa8b2 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h
+++ b/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h
@@ -31,9 +31,10 @@ public:
 
     // Parent transform that this transform is relative to, or nullptr if this
     // is the root transform.
-    const TransformPaintPropertyNode* parent() const { return m_parent.get(); }
+    TransformPaintPropertyNode* parent() const { return m_parent.get(); }
 
 private:
+
     TransformPaintPropertyNode(const TransformationMatrix& matrix, const FloatPoint3D& origin, PassRefPtr<TransformPaintPropertyNode> parent)
         : m_matrix(matrix), m_origin(origin), m_parent(parent) { }