Clean up remaining uses of WebCore namespace

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 "platform/heap/Handle.h"
 
-namespace WebCore {
+namespace blink {
 
 class DOMRectReadOnly : public GarbageCollected<DOMRectReadOnly> {
 public:
     static DOMRectReadOnly* create(double x, double y, double width, double height);
 
     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); }
 
     void trace(Visitor*) { }
 
 protected:
     DOMRectReadOnly(double x, double y, double width, double height);
 
     double m_x;
     double m_y;
     double m_width;
     double m_height;
 };
 
-} // namespace WebCore
+} // namespace blink
 
 #endif