(WIP) Paint invalidation for slimming paint v2

Source/core/layout/LayoutBlockFlow.cpp

 /*
  * Copyright (C) 2013 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 2011 matching lines @@
             && !floatingObject.layoutObject()->hasSelfPaintingLayer()
             && (floatingObject.isDirectlyContained() || (paintAllDescendants && floatingObject.isDescendant()))) {
 
             LayoutBox* floatingLayoutBox = floatingObject.layoutObject();
             floatingLayoutBox->setShouldDoFullPaintInvalidation();
             floatingLayoutBox->invalidatePaintForOverhangingFloats(false);
         }
     }
 }
 
+// TODO: Remove this (which is a kind of incremental invalidation) for slimming paint v2.
 void LayoutBlockFlow::invalidatePaintForOverflow()
 {
     // FIXME: We could tighten up the left and right invalidation points if we let layoutInlineChildren fill them in based off the particular lines
     // it had to lay out. We wouldn't need the hasOverflowClip() hack in that case either.
     LayoutUnit paintInvalidationLogicalLeft = logicalLeftVisualOverflow();
     LayoutUnit paintInvalidationLogicalRight = logicalRightVisualOverflow();
     if (hasOverflowClip()) {
         // If we have clipped overflow, we should use layout overflow as well, since visual overflow from lines didn't propagate to our block's overflow.
         // Note the old code did this as well but even for overflow:visible. The addition of hasOverflowClip() at least tightens up the hack a bit.
         // layoutInlineChildren should be patched to compute the entire paint invalidation rect.
@@ skipping 1015 matching lines @@
     FrameView* frameView = document().view();
     LayoutUnit top = (style()->position() == FixedPosition) ? 0 : frameView->scrollOffset().height();
     int visibleHeight = frameView->visibleContentRect(IncludeScrollbars).height();
     if (size().height() < visibleHeight)
         top += (visibleHeight - size().height()) / 2;
     setY(top);
     dialog->setCentered(top);
 }
 
 } // namespace blink