[WIP] Test moving stacking context flag update on ComputedStyle

third_party/WebKit/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/)
@@ skipping 430 matching lines @@
       !layoutParentStyleForcesZIndexToCreateStackingContext(
           layoutParentStyle)) {
     style.setIsStackingContext(false);
     // TODO(alancutter): Avoid altering z-index here.
     if (!style.hasAutoZIndex())
       style.setZIndex(0);
   } else if (!style.hasAutoZIndex()) {
     style.setIsStackingContext(true);
   }
 
+  style.updateIsStackingContext(
+      element == element->document().documentElement(),
+      element->isInTopLayer());
+
   if (style.overflowX() != EOverflow::kVisible ||
       style.overflowY() != EOverflow::kVisible)
     adjustOverflow(style);
 
   if (doesNotInheritTextDecoration(style, element))
     style.clearAppliedTextDecorations();
   else
     style.restoreParentTextDecorations(parentStyle);
   style.applyTextDecorations(
       parentStyle.visitedDependentColor(CSSPropertyTextDecorationColor),
@@ skipping 42 matching lines @@
       style.setDisplay(EDisplay::Block);
 
     // Columns don't apply to svg text elements.
     if (isSVGTextElement(*element))
       style.clearMultiCol();
   }
   adjustStyleForAlignment(style, parentStyle);
 }
 
 }  // namespace blink