[GeometryInterface] Add Constructor() at 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"
 
 #include "core/css/CSSIdentifierValue.h"
 #include "core/css/CSSToLengthConversionData.h"
 #include "core/css/CSSValueList.h"
 #include "core/css/parser/CSSParser.h"
@@ skipping 48 matching lines @@
         "for a 3D matrix.");
     return nullptr;
   }
   return new DOMMatrix(float64Array->data(), float64Array->length());
 }
 
 template <typename T>
 DOMMatrix::DOMMatrix(T sequence, int size)
     : DOMMatrixReadOnly(sequence, size) {}
 
-DOMMatrix::DOMMatrix(const TransformationMatrix& matrix, bool is2D) {
-  m_matrix = TransformationMatrix::create(matrix);
-  m_is2D = is2D;
-}
+DOMMatrix::DOMMatrix(const TransformationMatrix& matrix, bool is2D)
+    : DOMMatrixReadOnly(matrix, is2D) {}
 
 DOMMatrix* DOMMatrix::fromMatrix(DOMMatrixInit& other,
                                  ExceptionState& exceptionState) {
   validateAndFixup(other, exceptionState);
   if (exceptionState.hadException())
     return nullptr;
 
   if (other.is2D()) {
     return new DOMMatrix({other.m11(), other.m12(), other.m21(), other.m22(),
                           other.m41(), other.m42()},
@@ skipping 213 matching lines @@
 
   m_matrix->makeIdentity();
   operations.apply(FloatSize(0, 0), *m_matrix);
 
   m_is2D = !operations.has3DOperation();
 
   return this;
 }
 
 }  // namespace blink