Remove CSS regions support, keeping a bare minimum to support "region-based" multicol.

Source/core/css/resolver/StyleAdjuster.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 257 matching lines @@
         || style->hasTransformRelatedProperty()
         || style->hasMask()
         || style->clipPath()
         || style->boxReflect()
         || style->hasFilter()
         || style->hasBlendMode()
         || style->hasIsolation()
         || style->position() == StickyPosition
         || (style->position() == FixedPosition && e && e->document().settings() && e->document().settings()->fixedPositionCreatesStackingContext())
         || isInTopLayer(e, style)
-        || style->hasFlowFrom()
         ))
         style->setZIndex(0);
 
     // Textarea considers overflow visible as auto.
     if (e && e->hasTagName(textareaTag)) {
         style->setOverflowX(style->overflowX() == OVISIBLE ? OAUTO : style->overflowX());
         style->setOverflowY(style->overflowY() == OVISIBLE ? OAUTO : style->overflowY());
     }
 
     // For now, <marquee> requires an overflow clip to work properly.
@@ skipping 114 matching lines @@
     if (prop.isNamedGridArea() && !map.contains(prop.namedGridLine())) \
         style->setGrid##Prop(GridPosition());
 
     CLEAR_UNKNOWN_NAMED_AREA(columnStartPosition, ColumnStart);
     CLEAR_UNKNOWN_NAMED_AREA(columnEndPosition, ColumnEnd);
     CLEAR_UNKNOWN_NAMED_AREA(rowStartPosition, RowStart);
     CLEAR_UNKNOWN_NAMED_AREA(rowEndPosition, RowEnd);
 }
 
 }