Fix background-size serializing

third_party/WebKit/Source/core/css/StylePropertySerializer.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Research In Motion Limited. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. 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
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 641 matching lines @@
     bool hasCommonValue = true;
     const CSSValue* commonValue = nullptr;
 
     // Now stitch the properties together. Implicit initial values are flagged as such and
     // can safely be omitted.
     for (size_t layer = 0; layer < numLayers; layer++) {
         StringBuilder layerResult;
         bool useRepeatXShorthand = false;
         bool useRepeatYShorthand = false;
         bool useSingleWordShorthand = false;
+        bool foundPositionXCSSProperty = false;
         bool foundPositionYCSSProperty = false;
 
         for (unsigned propertyIndex = 0; propertyIndex < size; propertyIndex++) {
             const CSSValue* value = nullptr;
             CSSPropertyID property = shorthand.properties()[propertyIndex];
 
             // Get a CSSValue for this property and layer.
             if (values[propertyIndex]->isBaseValueList()) {
                 // Might return 0 if there is not an item for this layer for this property.
                 value = toCSSValueList(values[propertyIndex])->itemWithBoundsCheck(layer);
@@ skipping 30 matching lines @@
                     useRepeatXShorthand = true;
                     property = shorthand.properties()[++propertyIndex];
                 } else if (xId == CSSValueNoRepeat && yId == CSSValueRepeat) {
                     useRepeatYShorthand = true;
                     property = shorthand.properties()[++propertyIndex];
                 }
             }
 
             if (!(value->isInitialValue() && toCSSInitialValue(value)->isImplicit())) {
                 if (property == CSSPropertyBackgroundSize || property == CSSPropertyWebkitMaskSize) {
-                    if (foundPositionYCSSProperty)
+                    if (foundPositionYCSSProperty || foundPositionXCSSProperty)
                         layerResult.appendLiteral(" / ");
                     else
-                        continue;
+                        layerResult.appendLiteral(" 0% 0% / ");
                 } else if (!layerResult.isEmpty()) {
                     // Do this second to avoid ending up with an extra space in the output if we hit the continue above.
                     layerResult.append(' ');
                 }
 
                 if (useRepeatXShorthand) {
                     useRepeatXShorthand = false;
                     layerResult.append(getValueName(CSSValueRepeatX));
                 } else if (useRepeatYShorthand) {
                     useRepeatYShorthand = false;
                     layerResult.append(getValueName(CSSValueRepeatY));
                 } else {
                     if (useSingleWordShorthand)
                         useSingleWordShorthand = false;
                     layerResult.append(value->cssText());
                 }
+                if (property == CSSPropertyBackgroundPositionX || property == CSSPropertyWebkitMaskPositionX)
+                    foundPositionXCSSProperty = true;
                 if (property == CSSPropertyBackgroundPositionY || property == CSSPropertyWebkitMaskPositionY) {
                     foundPositionYCSSProperty = true;
                     // background-position is a special case. If only the first offset is specified,
                     // the second one defaults to "center", not the same value.
                     if (hasCommonValue && !value->isInitialValue() && !value->isInheritedValue())
                         hasCommonValue = false;
                 }
             }
 
             if (hasCommonValue && !commonValue)
@@ skipping 251 matching lines @@
             isInitialValue = false;
         if (!value->isInheritedValue())
             isInheritedValue = false;
         if (isImportant != m_propertySet.propertyIsImportant(shorthand.properties()[i]))
             return false;
     }
     return isInitialValue || isInheritedValue;
 }
 
 } // namespace blink