Remove code duplication from the customCSSText() methods of gradient classes.

Source/core/css/CSSGradientValue.h

 /*
  * Copyright (C) 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 77 matching lines @@
 
     void setFirstX(PassRefPtrWillBeRawPtr<CSSPrimitiveValue> val) { m_firstX = val; }
     void setFirstY(PassRefPtrWillBeRawPtr<CSSPrimitiveValue> val) { m_firstY = val; }
     void setSecondX(PassRefPtrWillBeRawPtr<CSSPrimitiveValue> val) { m_secondX = val; }
     void setSecondY(PassRefPtrWillBeRawPtr<CSSPrimitiveValue> val) { m_secondY = val; }
 
     void addStop(const CSSGradientColorStop& stop) { m_stops.append(stop); }
 
     unsigned stopCount() const { return m_stops.size(); }
 
+    void appendCSSTextForDeprecatedColorStops(StringBuilder&) const;
+
     void sortStopsIfNeeded();
 
     bool isRepeating() const { return m_repeating; }
 
     CSSGradientType gradientType() const { return m_gradientType; }
 
     bool isFixedSize() const { return false; }
     IntSize fixedSize(const RenderObject*) const { return IntSize(); }
 
     bool isPending() const { return false; }
@@ skipping 150 matching lines @@
 
     RefPtrWillBeMember<CSSPrimitiveValue> m_endHorizontalSize;
     RefPtrWillBeMember<CSSPrimitiveValue> m_endVerticalSize;
 };
 
 DEFINE_CSS_VALUE_TYPE_CASTS(CSSRadialGradientValue, isRadialGradientValue());
 
 } // namespace blink
 
 #endif // CSSGradientValue_h