Adding fromRect to DOMRect and DOMRectReadOnly interfaces following spec.

third_party/WebKit/Source/core/dom/DOMRectReadOnly.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 DOMRectReadOnly_h
 #define DOMRectReadOnly_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/CoreExport.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
+class DOMRectInit;
 class ScriptValue;
 class ScriptState;
 
 class CORE_EXPORT DOMRectReadOnly : public GarbageCollected<DOMRectReadOnly>,
                                     public ScriptWrappable {
   DEFINE_WRAPPERTYPEINFO();
 
  public:
   static DOMRectReadOnly* create(double x,
                                  double y,
                                  double width,
                                  double height);
+  static DOMRectReadOnly* fromRect(const DOMRectInit&);
 
   double x() const { return m_x; }
   double y() const { return m_y; }
   double width() const { return m_width; }
   double height() const { return m_height; }
 
   double top() const { return std::min(m_y, m_y + m_height); }
   double right() const { return std::max(m_x, m_x + m_width); }
   double bottom() const { return std::max(m_y, m_y + m_height); }
   double left() const { return std::min(m_x, m_x + m_width); }
 
   DEFINE_INLINE_TRACE() {}
 
   ScriptValue toJSONForBinding(ScriptState*) const;
 
  protected:
   DOMRectReadOnly(double x, double y, double width, double height);
 
   double m_x;
   double m_y;
   double m_width;
   double m_height;
 };
 
 }  // namespace blink
 
 #endif