Make CSSValueList store const CSSValues

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 379 matching lines @@
 
     StylePropertySet::PropertyReference contentProperty = propertySet.propertyAt(propertyIndex);
     CSSValue* contentValue = contentProperty.value();
 
     if (!contentValue->isValueList())
         return;
 
     for (auto& item : toCSSValueList(*contentValue)) {
         if (!item->isFunctionValue())
             continue;
-        CSSFunctionValue* functionValue = toCSSFunctionValue(item.get());
+        const CSSFunctionValue* functionValue = toCSSFunctionValue(item.get());
         if (functionValue->functionType() != CSSValueAttr)
             continue;
         ensureAttributeInvalidationSet(AtomicString(toCSSCustomIdentValue(functionValue->item(0))->value()), InvalidateDescendants).setInvalidatesSelf();
     }
 }
 
 std::pair<const CSSSelector*, RuleFeatureSet::UseFeaturesType>
 RuleFeatureSet::extractInvalidationSetFeatures(const CSSSelector& selector, InvalidationSetFeatures& features, PositionType position, CSSSelector::PseudoType pseudo)
 {
     bool foundFeatures = false;
@@ skipping 373 matching lines @@
     }
 }
 
 DEFINE_TRACE(RuleFeatureSet)
 {
     visitor->trace(siblingRules);
     visitor->trace(uncommonAttributeRules);
 }
 
 } // namespace blink