Remove support for pseudo classes in <content select>.

Source/core/html/HTMLContentElement.cpp

Index: Source/core/html/HTMLContentElement.cpp
diff --git a/Source/core/html/HTMLContentElement.cpp b/Source/core/html/HTMLContentElement.cpp
index a4f7c9f57abebd5fd3f32f685c978a736d0dbfb8..81fcd3360c0683e4e8c07e8bbc339f40f914695b 100644
--- a/Source/core/html/HTMLContentElement.cpp
+++ b/Source/core/html/HTMLContentElement.cpp
@@ -29,7 +29,6 @@
 
 #include "core/HTMLNames.h"
 #include "core/css/SelectorChecker.h"
-#include "core/css/SiblingTraversalStrategies.h"
 #include "core/css/parser/CSSParser.h"
 #include "core/dom/QualifiedName.h"
 #include "core/dom/shadow/ElementShadow.h"
@@ -101,13 +100,9 @@ bool HTMLContentElement::validateSelect() const
     if (!m_selectorList.isValid())
         return false;
 
-    bool allowAnyPseudoClasses = RuntimeEnabledFeatures::pseudoClassesInMatchingCriteriaInAuthorShadowTreesEnabled() || (containingShadowRoot() && containingShadowRoot()->type() == ShadowRoot::UserAgentShadowRoot);
-
     for (const CSSSelector* selector = m_selectorList.first(); selector; selector = m_selectorList.next(*selector)) {
         if (!selector->isCompound())
             return false;
-        if (allowAnyPseudoClasses)
-            continue;
         for (const CSSSelector* subSelector = selector; subSelector; subSelector = subSelector->tagHistory()) {
             if (includesDisallowedPseudoClass(*subSelector))
                 return false;
@@ -116,19 +111,15 @@ bool HTMLContentElement::validateSelect() const
     return true;
 }
 
-static inline bool checkOneSelector(const CSSSelector& selector, const WillBeHeapVector<RawPtrWillBeMember<Node>, 32>& siblings, int nth)
+// TODO(esprehn): element should really be const, but matching a selector is not
+// const for some SelectorCheckingModes (mainly ResolvingStyle) where it sets
+// dynamic restyle flags on elements.
+bool HTMLContentElement::matchSelector(Element& element) const
 {
-    Element* element = toElement(siblings[nth]);
     SelectorChecker selectorChecker(SelectorChecker::QueryingRules);
-    SelectorChecker::SelectorCheckingContext context(selector, element, SelectorChecker::VisitedMatchEnabled);
-    ShadowDOMSiblingTraversalStrategy strategy(siblings, nth);
-    return selectorChecker.match(context, strategy) == SelectorChecker::SelectorMatches;
-}
-
-bool HTMLContentElement::matchSelector(const WillBeHeapVector<RawPtrWillBeMember<Node>, 32>& siblings, int nth) const
-{
     for (const CSSSelector* selector = selectorList().first(); selector; selector = CSSSelectorList::next(*selector)) {
-        if (checkOneSelector(*selector, siblings, nth))
+        SelectorChecker::SelectorCheckingContext context(*selector, &element, SelectorChecker::VisitedMatchDisabled);

[esprehn, 2015/05/06 23:57:52]

I also switched this to VisitedMatchDisabled. Since pseudos were disabled for
non-UA code before and we never used them in UA code this was essentially
impossible, but now it really is impossible by forcing it off like
querySelector. Previously if the
pseudoClassesInMatchingCriteriaInAuthorShadowTrees flag was enabled we
accidentally allowed matching :visited which is a privacy leak.

+        if (selectorChecker.match(context) == SelectorChecker::SelectorMatches)
             return true;
     }
     return false;