Use 4 value syntax for getComputedStyle of background-position and -webkit-mask-position

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 583 matching lines @@
     case ReflectionRight:
         direction = cssValuePool().createIdentifierValue(CSSValueRight);
         break;
     }
 
     return CSSReflectValue::create(direction.release(), offset.release(), valueForNinePieceImage(reflection->mask(), style));
 }
 
 static PassRefPtr<CSSValueList> createPositionListForLayer(CSSPropertyID propertyID, const FillLayer* layer, const RenderStyle* style)
 {
+    ASSERT_UNUSED(propertyID, propertyID == CSSPropertyBackgroundPosition || propertyID == CSSPropertyWebkitMaskPosition);
     RefPtr<CSSValueList> positionList = CSSValueList::createSpaceSeparated();
-    if (layer->isBackgroundXOriginSet()) {
-        ASSERT_UNUSED(propertyID, propertyID == CSSPropertyBackgroundPosition || propertyID == CSSPropertyWebkitMaskPosition);
-        positionList->append(cssValuePool().createValue(layer->backgroundXOrigin()));
-    }
+    positionList->append(cssValuePool().createValue(layer->backgroundXOrigin()));
     positionList->append(zoomAdjustedPixelValueForLength(layer->xPosition(), style));
-    if (layer->isBackgroundYOriginSet()) {
-        ASSERT(propertyID == CSSPropertyBackgroundPosition || propertyID == CSSPropertyWebkitMaskPosition);
-        positionList->append(cssValuePool().createValue(layer->backgroundYOrigin()));
-    }
+    positionList->append(cssValuePool().createValue(layer->backgroundYOrigin()));
     positionList->append(zoomAdjustedPixelValueForLength(layer->yPosition(), style));
     return positionList.release();
 }
 
 static PassRefPtr<CSSValue> valueForPositionOffset(RenderStyle* style, CSSPropertyID propertyID, const RenderObject* renderer, RenderView* renderView)
 {
     if (!style)
         return 0;
 
     Length l;
@@ skipping 2600 matching lines @@
     static const CSSPropertyID propertiesAfterSlashSeperator[3] = { CSSPropertyBackgroundSize, CSSPropertyBackgroundOrigin,
                                                                     CSSPropertyBackgroundClip };
 
     RefPtr<CSSValueList> list = CSSValueList::createSlashSeparated();
     list->append(valuesForShorthandProperty(StylePropertyShorthand(CSSPropertyBackground, propertiesBeforeSlashSeperator, WTF_ARRAY_LENGTH(propertiesBeforeSlashSeperator))));
     list->append(valuesForShorthandProperty(StylePropertyShorthand(CSSPropertyBackground, propertiesAfterSlashSeperator, WTF_ARRAY_LENGTH(propertiesAfterSlashSeperator))));
     return list.release();
 }
 
 } // namespace WebCore