Add UseCounter for case-insensitive attribute value selector matching

Source/core/css/SelectorChecker.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, 2013 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 419 matching lines @@
     ASSERT(selectorAttr.localName() != starAtom); // Should not be possible from the CSS grammar.
 
     // Synchronize the attribute in case it is lazy-computed.
     // Currently all lazy properties have a null namespace, so only pass localName().
     element.synchronizeAttribute(selectorAttr.localName());
 
     if (!element.hasAttributesWithoutUpdate())
         return false;
 
     const AtomicString& selectorValue =  selector.value();
-    // Case sensitivity for attribute matching is looser than hasAttribute or
-    // Element::shouldIgnoreAttributeCase() for now. Unclear if that's correct.
-    bool caseSensitive = !element.document().isHTMLDocument() || HTMLDocument::isCaseSensitiveAttribute(selectorAttr);
 
     for (size_t i = 0; i < element.attributeCount(); ++i) {
         const Attribute* attributeItem = element.attributeItem(i);
 
         if (!attributeItem->matches(selectorAttr))
             continue;
 
-        if (attributeValueMatches(attributeItem, match, selectorValue, caseSensitive))
+        if (attributeValueMatches(attributeItem, match, selectorValue, true))
             return true;
+
+        // Case sensitivity for attribute matching is looser than hasAttribute or
+        // Element::shouldIgnoreAttributeCase() for now. Unclear if that's correct.
+        bool caseSensitive = !element.document().isHTMLDocument() || HTMLDocument::isCaseSensitiveAttribute(selectorAttr);
+
+        // If case-insensitive, re-check, and count if result differs.
+        // See http://code.google.com/p/chromium/issues/detail?id=327060
+        if (!caseSensitive && attributeValueMatches(attributeItem, match, selectorValue, false)) {
+            UseCounter::count(element.document(), UseCounter::CaseInsensitiveAttrSelectorMatch);
+            return true;
+        }
     }
 
     return false;
 }
 
 template<typename SiblingTraversalStrategy>
 bool SelectorChecker::checkOne(const SelectorCheckingContext& context, const SiblingTraversalStrategy& siblingTraversalStrategy, unsigned* specificity) const
 {
     ASSERT(context.element);
     Element& element = *context.element;
@@ skipping 606 matching lines @@
     return element.focused() && isFrameFocused(element);
 }
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const DOMSiblingTraversalStrategy&, MatchResult*) const;
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const ShadowDOMSiblingTraversalStrategy&, MatchResult*) const;
 
 }