Change clip rect computation for multicol

Source/core/rendering/RenderLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 2598 matching lines @@
         colRect.moveBy(layerOffset);
 
         LayoutRect localDirtyRect(paintingInfo.paintDirtyRect);
         localDirtyRect.intersect(colRect);
 
         if (!localDirtyRect.isEmpty()) {
             GraphicsContextStateSaver stateSaver(*context);
 
             // Each strip pushes a clip, since column boxes are specified as being
             // like overflow:hidden.
-            context->clip(pixelSnappedIntRect(colRect));
+            context->clip(enclosingIntRect(colRect));
 
             if (!colIndex) {
                 // Apply a translation transform to change where the layer paints.
                 TransformationMatrix oldTransform;
                 bool oldHasTransform = childLayer->transform();
                 if (oldHasTransform)
                     oldTransform = *childLayer->transform();
                 TransformationMatrix newTransform(oldTransform);
                 newTransform.translateRight(roundToInt(offset.width()), roundToInt(offset.height()));
 
@@ skipping 1391 matching lines @@
     }
 }
 
 void showLayerTree(const WebCore::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif