Only accept inherit/initial/unset in single value declarations

Source/core/css/parser/CSSPropertyParser.cpp

 /*
  * Copyright (C) 2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
  * Copyright (C) 2012 Intel Corporation. All rights reserved.
  *
@@ skipping 428 matching lines @@
 
         return parseViewportProperty(propId, important);
     }
 
     // Note: m_parsedCalculation is used to pass the calc value to validUnit and then cleared at the end of this function.
     // FIXME: This is to avoid having to pass parsedCalc to all validUnit callers.
     ASSERT(!m_parsedCalculation);
 
     CSSValueID id = value->id;
 
-    int num = inShorthand() ? 1 : m_valueList->size();
-
     if (id == CSSValueInherit) {
-        if (num != 1)
+        if (m_valueList->size() != 1)
             return false;
         addExpandedPropertyForValue(propId, cssValuePool().createInheritedValue(), important);
         return true;
     } else if (id == CSSValueInitial) {
-        if (num != 1)
+        if (m_valueList->size() != 1)
             return false;
         addExpandedPropertyForValue(propId, cssValuePool().createExplicitInitialValue(), important);
         return true;
     } else if (id == CSSValueUnset) {
-        if (num != 1)
+        if (m_valueList->size() != 1)
             return false;
         addExpandedPropertyForValue(propId, cssValuePool().createUnsetValue(), important);
         return true;
     }
 
+    int num = inShorthand() ? 1 : m_valueList->size();
+
     if (CSSParserFastPaths::isKeywordPropertyID(propId)) {
         if (!CSSParserFastPaths::isValidKeywordPropertyAndValue(propId, id))
             return false;
         if (m_valueList->next() && !inShorthand())
             return false;
         addProperty(propId, cssValuePool().createIdentifierValue(id), important);
         return true;
     }
 
     bool validPrimitive = false;
@@ skipping 8007 matching lines @@
         }
     }
 
     if (!list->length())
         return nullptr;
 
     return list.release();
 }
 
 } // namespace blink