Implement inverse & invertSelf function in DOMMatrix & DOMMatrixReadOnly.

third_party/WebKit/Source/core/dom/DOMMatrix.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 "core/dom/DOMMatrix.h"
 
 namespace blink {
 
 DOMMatrix* DOMMatrix::create()
 {
@@ skipping 100 matching lines @@
     m_matrix->skewX(sx);
     return this;
 }
 
 DOMMatrix* DOMMatrix::skewYSelf(double sy)
 {
     m_matrix->skewY(sy);
     return this;
 }
 
+DOMMatrix* DOMMatrix::invertSelf()
+{
+    if (m_matrix->isInvertible()) {
+        m_matrix = TransformationMatrix::create(m_matrix->inverse());
+    } else {
+        setM11(std::nan(""));

[dominicc (has gone to gerrit), 2016/08/30 02:22:09]

Hmm, I haven't done any numerical programming with C++, but this is a bit of a
surprise. There's no constant or macro for this?

[Hwanseung Lee, 2016/08/30 12:47:05]

Done.

+        setM12(std::nan(""));
+        setM13(std::nan(""));
+        setM14(std::nan(""));
+        setM21(std::nan(""));
+        setM22(std::nan(""));
+        setM23(std::nan(""));
+        setM24(std::nan(""));
+        setM31(std::nan(""));
+        setM32(std::nan(""));
+        setM33(std::nan(""));
+        setM34(std::nan(""));
+        setM41(std::nan(""));
+        setM42(std::nan(""));
+        setM43(std::nan(""));
+        setM44(std::nan(""));
+        setIs2D(false);
+    }
+    return this;
+}
+
 } // namespace blink