[CSS Grid Layout] Remove stack from grid-auto-flow syntax

Source/core/css/CSSComputedStyleDeclaration.cpp

 /*
  * Copyright (C) 2004 Zack Rusin <zack@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  * Copyright (C) 2011 Sencha, Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
@@ skipping 1932 matching lines @@
             RefPtrWillBeRawPtr<CSSValueList> list = CSSValueList::createSpaceSeparated();
             switch (style->gridAutoFlow()) {
             case AutoFlowRow:
             case AutoFlowRowDense:
                 list->append(cssValuePool().createIdentifierValue(CSSValueRow));
                 break;
             case AutoFlowColumn:
             case AutoFlowColumnDense:
                 list->append(cssValuePool().createIdentifierValue(CSSValueColumn));
                 break;
-            case AutoFlowStackRow:
-            case AutoFlowStackColumn:
-                list->append(cssValuePool().createIdentifierValue(CSSValueStack));
-                break;
             default:
                 ASSERT_NOT_REACHED();
             }
 
             switch (style->gridAutoFlow()) {
             case AutoFlowRowDense:
             case AutoFlowColumnDense:
                 list->append(cssValuePool().createIdentifierValue(CSSValueDense));
                 break;
-            case AutoFlowStackRow:
-                list->append(cssValuePool().createIdentifierValue(CSSValueRow));
-                break;
-            case AutoFlowStackColumn:
-                list->append(cssValuePool().createIdentifierValue(CSSValueColumn));
-                break;
             default:
                 // Do nothing.
                 break;
             }
 
             return list.release();
         }
         // Specs mention that getComputedStyle() should return the used value of the property instead of the computed
         // one for grid-definition-{rows|columns} but not for the grid-auto-{rows|columns} as things like
         // grid-auto-columns: 2fr; cannot be resolved to a value in pixels as the '2fr' means very different things
@@ skipping 1081 matching lines @@
     return list.release();
 }
 
 void CSSComputedStyleDeclaration::trace(Visitor* visitor)
 {
     visitor->trace(m_node);
     CSSStyleDeclaration::trace(visitor);
 }
 
 } // namespace blink