Fix scroll origin, overflow rects, and coordinate flipping for flexbox.

third_party/WebKit/Source/core/layout/LayoutBox.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 937 matching lines @@
 bool LayoutBox::needsPreferredWidthsRecalculation() const
 {
     return style()->paddingStart().hasPercent() || style()->paddingEnd().hasPercent();
 }
 
 IntSize LayoutBox::scrolledContentOffset() const
 {
     ASSERT(hasOverflowClip());
     ASSERT(hasLayer());
     // FIXME: Return DoubleSize here. crbug.com/414283.
-    return flooredIntSize(getScrollableArea()->scrollOffset());
+    PaintLayerScrollableArea* scrollableArea = getScrollableArea();
+    IntSize result = flooredIntSize(scrollableArea->scrollOffset()) + scrollableArea->originAdjustmentForScrollbars();
+    if (isHorizontalWritingMode() && shouldPlaceBlockDirectionScrollbarOnLogicalLeft())

[leviw_travelin_and_unemployed, 2016/04/28 22:12:12]

Probably deserves a comment.

+        result.expand(-verticalScrollbarWidth(), 0);
+    return result;
 }
 
 bool LayoutBox::mapScrollingContentsRectToBoxSpace(LayoutRect& rect, ApplyOverflowClipFlag applyOverflowClip, VisualRectFlags visualRectFlags) const
 {
     if (!hasOverflowClip())
         return true;
 
     LayoutSize offset = LayoutSize(-scrolledContentOffset());
     if (UNLIKELY(hasFlippedBlocksWritingMode()))
         offset.setWidth(-offset.width());
@@ skipping 3761 matching lines @@
 
 void LayoutBox::clearPercentHeightDescendants()
 {
     for (LayoutObject* curr = slowFirstChild(); curr; curr = curr->nextInPreOrder(this)) {
         if (curr->isBox())
             toLayoutBox(curr)->removeFromPercentHeightContainer();
     }
 }
 
 } // namespace blink