Implement flip*() methods in DOMMatrixReaOnly.

Source/core/dom/DOMMatrixReadOnly.cpp

 // Copyright 2014 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.
 
 #include "config.h"
 #include "core/dom/DOMMatrix.h"
 
 namespace blink {
 
 bool DOMMatrixReadOnly::is2D() const
@@ skipping 74 matching lines @@
 DOMMatrix* DOMMatrixReadOnly::skewX(double sx)
 {
     return DOMMatrix::create(this)->skewXSelf(sx);
 }
 
 DOMMatrix* DOMMatrixReadOnly::skewY(double sy)
 {
     return DOMMatrix::create(this)->skewYSelf(sy);
 }
 
+DOMMatrix* DOMMatrixReadOnly::flipX()
+{
+    return scaleNonUniform(-1);
+}
+
+DOMMatrix* DOMMatrixReadOnly::flipY()
+{
+    return scaleNonUniform(1, -1);
+}
+
 } // namespace blink