Remove unnecessary RenderFlowThread usage and inclusion.

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 2537 matching lines @@
 
     // We need to stop here, since we don't want to increase the height of the table
     // artificially.  We're going to rely on this cell getting expanded to some new
     // height, and then when we lay out again we'll use the calculation below.
     if (isTableCell() && (h.isAuto() || h.isPercent())) {
         if (hasOverrideHeight())
             return overrideLogicalContentHeight();
         return logicalHeight() - borderAndPaddingLogicalHeight();
     }
 
-    if (h.isPercent() && isOutOfFlowPositioned() && !isRenderFlowThread()) {
+    if (h.isPercent() && isOutOfFlowPositioned()) {
         // FIXME: This is wrong if the containingBlock has a perpendicular writing mode.
         LayoutUnit availableHeight = containingBlockLogicalHeightForPositioned(containingBlock());
         return adjustContentBoxLogicalHeightForBoxSizing(valueForLength(h, availableHeight));
     }
 
     LayoutUnit heightIncludingScrollbar = computeContentAndScrollbarLogicalHeightUsing(h, -1);
     if (heightIncludingScrollbar != -1)
         return std::max<LayoutUnit>(0, adjustContentBoxLogicalHeightForBoxSizing(heightIncludingScrollbar) - scrollbarLogicalHeight());
 
     // FIXME: Check logicalTop/logicalBottom here to correctly handle vertical writing-mode.
@@ skipping 1871 matching lines @@
 
     setLogicalTop(oldLogicalTop);
     setLogicalWidth(oldLogicalWidth);
     setMarginLeft(oldMarginLeft);
     setMarginRight(oldMarginRight);
 
     return borderBox;
 }
 
 } // namespace blink