Make the constructor of a LayoutRect from an IntRect explicit.

Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 277 matching lines @@
 void HTMLCanvasElement::didFinalizeFrame()
 {
     if (m_dirtyRect.isEmpty())
         return;
 
     // Propagate the m_dirtyRect accumulated so far to the compositor
     // before restarting with a blank dirty rect.
     FloatRect srcRect(0, 0, size().width(), size().height());
     m_dirtyRect.intersect(srcRect);
     if (LayoutBox* ro = layoutBox()) {
-        FloatRect mappedDirtyRect = mapRect(m_dirtyRect, srcRect, ro->contentBoxRect());
+        LayoutRect mappedDirtyRect(enclosingIntRect(mapRect(m_dirtyRect, srcRect, ro->contentBoxRect())));
         // For querying Layer::compositingState()
         // FIXME: is this invalidation using the correct compositing state?
         DisableCompositingQueryAsserts disabler;
-        ro->invalidatePaintRectangle(enclosingIntRect(mappedDirtyRect));
+        ro->invalidatePaintRectangle(mappedDirtyRect);
     }
     notifyObserversCanvasChanged(m_dirtyRect);
     m_dirtyRect = FloatRect();
 }
 
 void HTMLCanvasElement::restoreCanvasMatrixClipStack()
 {
     if (m_context && m_context->is2d())
         toCanvasRenderingContext2D(m_context.get())->restoreCanvasMatrixClipStack();
 }
@@ skipping 572 matching lines @@
 {
     return FloatSize(width(), height());
 }
 
 bool HTMLCanvasElement::isOpaque() const
 {
     return m_context && !m_context->hasAlpha();
 }
 
 } // blink