Adjust DOMWindow properties to emulate old style pinch semantics

Source/core/frame/PinchViewport.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 96 matching lines @@
     float scale() const { return m_scale; }
 
     void registerLayersWithTreeView(blink::WebLayerTreeView*) const;
     void clearLayersForTreeView(blink::WebLayerTreeView*) const;
 
     // The portion of the unzoomed frame visible in the inner "pinch" viewport,
     // in partial CSS pixels. Relative to the main frame.
     FloatRect visibleRect() const;
 
     // The viewport rect relative to the document origin, in partial CSS pixels.
+    // FIXME: This should be a DoubleRect since scroll offsets are now doubles.
     FloatRect visibleRectInDocument() const;
 
     // Scroll the main frame and pinch viewport so that the given rect in the
     // top-level document is centered in the viewport. This method will avoid
     // scrolling the pinch viewport unless necessary.
     void scrollIntoView(const LayoutRect&);
 
     // Clamp the given point, in document coordinates, to the maximum/minimum
     // scroll extents of the viewport within the document.
     IntPoint clampDocumentOffsetAtScale(const IntPoint& offset, float scale);
@@ skipping 61 matching lines @@
     // Offset of the pinch viewport from the main frame's origin, in CSS pixels.
     FloatPoint m_offset;
     float m_scale;
     IntSize m_size;
     float m_topControlsAdjustment;
 };
 
 } // namespace blink
 
 #endif // PinchViewport_h