Consider subpixel accumulation when invalidating paint

Source/core/rendering/RenderBox.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, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. 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 4074 matching lines @@
         LayoutUnit borderWidth = std::max<LayoutUnit>(borderRight(), std::max<LayoutUnit>(valueForLength(style()->borderTopRightRadius().width(), boxWidth), valueForLength(style()->borderBottomRightRadius().width(), boxWidth)));
         LayoutUnit decorationsLeftWidth = std::max<LayoutUnit>(-outlineStyle->outlineOffset(), borderWidth + minInsetRightShadowExtent) + std::max<LayoutUnit>(outlineWidth, -shadowLeft);
         LayoutUnit decorationsRightWidth = std::max<LayoutUnit>(-outlineStyle->outlineOffset(), borderWidth + minInsetRightShadowExtent) + std::max<LayoutUnit>(outlineWidth, shadowRight);
         LayoutRect rightRect(newBounds.x() + std::min(newBounds.width(), oldBounds.width()) - decorationsLeftWidth,
             newBounds.y(),
             deltaWidth + decorationsLeftWidth + decorationsRightWidth,
             std::max(newBounds.height(), oldBounds.height()));
         LayoutUnit right = std::min<LayoutUnit>(newBounds.maxX(), oldBounds.maxX());
         if (rightRect.x() < right) {
             rightRect.setWidth(std::min(rightRect.width(), right - rightRect.x()));
-            invalidatePaintUsingContainer(paintInvalidationContainer, pixelSnappedIntRect(rightRect), InvalidationIncremental);
+            invalidatePaintUsingContainer(paintInvalidationContainer, rightRect, InvalidationIncremental);
         }
     }
 
     LayoutUnit deltaHeight = absoluteValue(newBounds.height() - oldBounds.height());
     if (deltaHeight) {
         LayoutUnit shadowTop;
         LayoutUnit shadowBottom;
         style()->getBoxShadowVerticalExtent(shadowTop, shadowBottom);
         LayoutUnit boxHeight = height();
         LayoutUnit minInsetBottomShadowExtent = std::min<LayoutUnit>(-insetShadowExtent.bottom(), std::min<LayoutUnit>(newBounds.height(), oldBounds.height()));
         LayoutUnit borderHeight = std::max<LayoutUnit>(borderBottom(), std::max<LayoutUnit>(valueForLength(style()->borderBottomLeftRadius().height(), boxHeight), valueForLength(style()->borderBottomRightRadius().height(), boxHeight)));
         LayoutUnit decorationsTopHeight = std::max<LayoutUnit>(-outlineStyle->outlineOffset(), borderHeight + minInsetBottomShadowExtent) + std::max<LayoutUnit>(outlineWidth, -shadowTop);
         LayoutUnit decorationsBottomHeight = std::max<LayoutUnit>(-outlineStyle->outlineOffset(), borderHeight + minInsetBottomShadowExtent) + std::max<LayoutUnit>(outlineWidth, shadowBottom);
         LayoutRect bottomRect(newBounds.x(),
             std::min(newBounds.maxY(), oldBounds.maxY()) - decorationsTopHeight,
             std::max(newBounds.width(), oldBounds.width()),
             deltaHeight + decorationsTopHeight + decorationsBottomHeight);
         LayoutUnit bottom = std::min(newBounds.maxY(), oldBounds.maxY());
         if (bottomRect.y() < bottom) {
             bottomRect.setHeight(std::min(bottomRect.height(), bottom - bottomRect.y()));
-            invalidatePaintUsingContainer(paintInvalidationContainer, pixelSnappedIntRect(bottomRect), InvalidationIncremental);
+            invalidatePaintUsingContainer(paintInvalidationContainer, bottomRect, InvalidationIncremental);
         }
     }
 }
 
 void RenderBox::markForPaginationRelayoutIfNeeded(SubtreeLayoutScope& layoutScope)
 {
     ASSERT(!needsLayout());
     // If fragmentation height has changed, we need to lay out. No need to enter the renderer if it
     // is childless, though.
     if (view()->layoutState()->pageLogicalHeightChanged() && slowFirstChild())
@@ skipping 540 matching lines @@
         return 0;
 
     if (!layoutState && !flowThreadContainingBlock())
         return 0;
 
     RenderBlock* containerBlock = containingBlock();
     return containerBlock->offsetFromLogicalTopOfFirstPage() + logicalTop();
 }
 
 } // namespace WebCore