Round off error while calculating the background-size: contain/cover.

Source/core/rendering/RenderBoxModelObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 916 matching lines @@
             // If the image has neither an intrinsic width nor an intrinsic height, its size is determined as for ‘contain’.
             type = Contain;
         }
         case Contain:
         case Cover: {
             float horizontalScaleFactor = imageIntrinsicSize.width()
                 ? static_cast<float>(positioningAreaSize.width()) / imageIntrinsicSize.width() : 1;
             float verticalScaleFactor = imageIntrinsicSize.height()
                 ? static_cast<float>(positioningAreaSize.height()) / imageIntrinsicSize.height() : 1;
             float scaleFactor = type == Contain ? min(horizontalScaleFactor, verticalScaleFactor) : max(horizontalScaleFactor, verticalScaleFactor);
-            return IntSize(max(1, static_cast<int>(imageIntrinsicSize.width() * scaleFactor)), max(1, static_cast<int>(imageIntrinsicSize.height() * scaleFactor)));
+            return IntSize(max(1, static_cast<int>(round(imageIntrinsicSize.width() * scaleFactor))), max(1, static_cast<int>(round(imageIntrinsicSize.height() * scaleFactor))));

[eseidel, 2013/09/18 18:59:45]

should this just be lround?

        }
     }
 
     ASSERT_NOT_REACHED();
     return IntSize();
 }
 
 void RenderBoxModelObject::BackgroundImageGeometry::setNoRepeatX(int xOffset)
 {
     m_destRect.move(max(xOffset, 0), 0);
@@ skipping 1838 matching lines @@
     ASSERT(!beforeChild || toBoxModelObject == beforeChild->parent());
     for (RenderObject* child = startChild; child && child != endChild; ) {
         // Save our next sibling as moveChildTo will clear it.
         RenderObject* nextSibling = child->nextSibling();
         moveChildTo(toBoxModelObject, child, beforeChild, fullRemoveInsert);
         child = nextSibling;
     }
 }
 
 } // namespace WebCore