Adding fromPoint to DOMPoint and DOMPointReadOnly interfaces following spec.

third_party/WebKit/Source/core/dom/DOMPointReadOnly.h

 // 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.
 
 #ifndef DOMPointReadOnly_h
 #define DOMPointReadOnly_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/CoreExport.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
+class DOMPointInit;
+
 class CORE_EXPORT DOMPointReadOnly : public GarbageCollected<DOMPointReadOnly>,
                                      public ScriptWrappable {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
   static DOMPointReadOnly* create(double x, double y, double z, double w);
+  static DOMPointReadOnly* fromPoint(const DOMPointInit&);
 
   double x() const { return m_x; }
   double y() const { return m_y; }
   double z() const { return m_z; }
   double w() const { return m_w; }
 
   DEFINE_INLINE_TRACE() {}
 
  protected:
   DOMPointReadOnly(double x, double y, double z, double w);
 
   double m_x;
   double m_y;
   double m_z;
   double m_w;
 };
 
 }  // namespace blink
 
 #endif