Make the constructor of a LayoutRect from an IntRect explicit.

Source/platform/geometry/LayoutRect.h

 /*
  * Copyright (c) 2012, 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 31 matching lines @@
 
 class PLATFORM_EXPORT LayoutRect {
 public:
     LayoutRect() { }
     LayoutRect(const LayoutPoint& location, const LayoutSize& size)
         : m_location(location), m_size(size) { }
     LayoutRect(LayoutUnit x, LayoutUnit y, LayoutUnit width, LayoutUnit height)
         : m_location(LayoutPoint(x, y)), m_size(LayoutSize(width, height)) { }
     LayoutRect(const FloatPoint& location, const FloatSize& size)
         : m_location(location), m_size(size) { }
-    LayoutRect(const IntRect& rect) : m_location(rect.location()), m_size(rect.size()) { }
+    explicit LayoutRect(const IntRect& rect) : m_location(rect.location()), m_size(rect.size()) { }
 
     explicit LayoutRect(const FloatRect&); // don't do this implicitly since it's lossy
 
     LayoutPoint location() const { return m_location; }
     LayoutSize size() const { return m_size; }
 
     IntPoint pixelSnappedLocation() const { return roundedIntPoint(m_location); }
     IntSize pixelSnappedSize() const { return IntSize(snapSizeToPixel(m_size.width(), m_location.x()), snapSizeToPixel(m_size.height(), m_location.y())); }
 
     void setLocation(const LayoutPoint& location) { m_location = location; }
@@ skipping 178 matching lines @@
 }
 
 inline IntRect pixelSnappedIntRect(LayoutPoint location, LayoutSize size)
 {
     return IntRect(roundedIntPoint(location), pixelSnappedIntSize(size, location));
 }
 
 } // namespace blink
 
 #endif // LayoutRect_h