Added parseShorthand method from the parser to CSSPropertyAPI.h.

third_party/WebKit/Source/core/css/properties/CSSPropertyAPI.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 CSSPropertyAPI_h
 #define CSSPropertyAPI_h
 
 #include "core/CSSPropertyNames.h"
 #include "wtf/Allocator.h"
 
@@ skipping 23 matching lines @@
  public:
   // Parses a single CSS property and returns the corresponding CSSValue. If the
   // input is invalid it returns nullptr.
   static const CSSValue* parseSingleValue(CSSParserTokenRange&,
                                           const CSSParserContext*) {
     // No code should reach here, since properties either have their own
     // implementations of this method or store nullptr in their descriptor.
     NOTREACHED();
     return nullptr;
   }
+
+  static bool parseShorthand(bool,
+                             CSSParserTokenRange&,
+                             const CSSParserContext*) {
+    // No code should reach here, since properties either have their own
+    // implementations of this method or store nullptr in their descriptor.
+    NOTREACHED();
+    return false;
+  }
 };
 
 }  // namespace blink
 
 #endif  // CSSPropertyAPI_h