Support invalidation sets for simple class selectors.

Source/core/css/RuleFeature.cpp

Index: Source/core/css/RuleFeature.cpp
diff --git a/Source/core/css/RuleFeature.cpp b/Source/core/css/RuleFeature.cpp
index 1395acf0e6f59aca9dfcef749802b97bc3626a39..82d741de855404aed1990d05ff6d7e40985153ae 100644
--- a/Source/core/css/RuleFeature.cpp
+++ b/Source/core/css/RuleFeature.cpp
@@ -54,7 +54,6 @@ static bool isSkippableComponentForInvalidation(const CSSSelector& selector)
 static bool supportsClassDescendantInvalidation(const CSSSelector& selector)
 {
     bool foundDescendantRelation = false;

[chrishtr, 2014/02/19 17:50:44]

remove these variables

[rune, 2014/02/19 18:47:40]

See other comment.

-    bool foundAncestorIdent = false;
     bool foundIdent = false;
     for (const CSSSelector* component = &selector; component; component = component->tagHistory()) {
 
@@ -65,8 +64,6 @@ static bool supportsClassDescendantInvalidation(const CSSSelector& selector)
         if (component->m_match == CSSSelector::Class) {
             if (!foundDescendantRelation)
                 foundIdent = true;

[chrishtr, 2014/02/19 17:50:44]

return true, remove if (!foundDescendantRelation)

[rune, 2014/02/19 18:47:40]

We still need to continue to look for adjacent combinators and
!isSkippableComponentForInvalidation() for which we need to return false even if
foundIdent is true.

[chrishtr, 2014/02/19 18:54:01]

Oh right, good point.

-            else
-                foundAncestorIdent = true;
         } else if (!isSkippableComponentForInvalidation(*component)) {
             return false;
         }
@@ -82,7 +79,7 @@ static bool supportsClassDescendantInvalidation(const CSSSelector& selector)
             return false;
         }
     }
-    return foundDescendantRelation && foundAncestorIdent && foundIdent;
+    return foundIdent;

[chrishtr, 2014/02/19 17:50:44]

remove this line

[rune, 2014/02/19 18:47:40]

See other comment.

 }
 
 void extractClassIdOrTag(const CSSSelector& selector, Vector<AtomicString>& classes, AtomicString& id, AtomicString& tagName)