Have ElementData::attributeItem() return a reference

Source/core/css/SelectorChecker.h

Index: Source/core/css/SelectorChecker.h
diff --git a/Source/core/css/SelectorChecker.h b/Source/core/css/SelectorChecker.h
index fd98ccc4a96b2400f3f633a523305affe447fe33..28f78cc47ee67d7f6211ec532fc54467e8b3c87d 100644
--- a/Source/core/css/SelectorChecker.h
+++ b/Source/core/css/SelectorChecker.h
@@ -171,8 +171,8 @@ inline bool SelectorChecker::checkExactAttribute(const Element& element, const Q
         return false;
     unsigned size = element.attributeCount();
     for (unsigned i = 0; i < size; ++i) {
-        const Attribute* attribute = element.attributeItem(i);
-        if (attribute->matches(selectorAttributeName) && (!value || attribute->value().impl() == value))
+        const Attribute& attribute = element.attributeItem(i);
+        if (attribute.matches(selectorAttributeName) && (!value || attribute.value().impl() == value))
             return true;
     }
     return false;