Implement CSSPaintValue and add a layout test.

third_party/WebKit/Source/core/css/cssom/StyleValueFactory.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef StyleValueFactory_h
 #define StyleValueFactory_h
 
 #include "core/CSSPropertyNames.h"
 #include "core/css/cssom/CSSStyleValue.h"
 #include "wtf/Allocator.h"
 
 namespace blink {
 
 class CSSValue;
 
-class StyleValueFactory {
+class CORE_EXPORT StyleValueFactory {
   STATIC_ONLY(StyleValueFactory);
 
  public:
   static CSSStyleValueVector cssValueToStyleValueVector(CSSPropertyID,
                                                         const CSSValue&);
   // If you don't have complex CSS properties, use this one.
   static CSSStyleValueVector cssValueToStyleValueVector(const CSSValue&);
 };
 
 }  // namespace blink
 
 #endif