Add localToAbsoluteTransform and localToAncestorTransform.

third_party/WebKit/Source/platform/transforms/TransformationMatrix.cpp

Index: third_party/WebKit/Source/platform/transforms/TransformationMatrix.cpp
diff --git a/third_party/WebKit/Source/platform/transforms/TransformationMatrix.cpp b/third_party/WebKit/Source/platform/transforms/TransformationMatrix.cpp
index 541a68bc09cbc63701912c262f1d5b0e394260be..f013a3f35f9a8031ad283e9ef993044fa5282d7b 100644
--- a/third_party/WebKit/Source/platform/transforms/TransformationMatrix.cpp
+++ b/third_party/WebKit/Source/platform/transforms/TransformationMatrix.cpp
@@ -1398,6 +1398,17 @@ AffineTransform TransformationMatrix::toAffineTransform() const
                            m_matrix[1][1], m_matrix[3][0], m_matrix[3][1]);
 }
 
+void TransformationMatrix::flattenTo2d()
+{
+    m_matrix[2][0] = 0;
+    m_matrix[2][1] = 0;
+    m_matrix[0][2] = 0;
+    m_matrix[1][2] = 0;
+    m_matrix[2][2] = 1;
+    m_matrix[3][2] = 0;
+    m_matrix[2][3] = 0;
+}
+
 static inline void blendFloat(double& from, double to, double progress)
 {
     if (from != to)