Fix issue in which removing a class does not always invalidate style

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 b52569a0034cea47262ee54d626699f31eaf38c5..ea0edf74cc9cbe28cbadd82f0fc6e94542f40c6f 100644
--- a/Source/core/css/RuleFeature.cpp
+++ b/Source/core/css/RuleFeature.cpp
@@ -380,9 +380,12 @@ bool RuleFeatureSet::invalidateStyleForClassChangeOnChildren(Element* element, V
 
 bool RuleFeatureSet::invalidateStyleForClassChange(Element* element, Vector<AtomicString>& invalidationClasses, bool foundInvalidationSet)
 {
+    bool thisElementNeedsStyleRecalc = false;
     int oldSize = invalidationClasses.size();
+
     if (element->needsStyleInvalidation()) {
         if (InvalidationList* invalidationList = m_pendingInvalidationMap.get(element)) {
+            thisElementNeedsStyleRecalc = true;
             foundInvalidationSet = true;

[esprehn, 2014/02/18 22:52:33]

Isn't this bool identical to foundInvalidationSet then?

[chrishtr, 2014/02/18 23:14:31]

No, because not all elements in the subtree of an element with a pending
invalidation list needs style recalc. The code recalculates style if one of
these is true:

1. The element has a pending invalidation list
2. The element has a class matching one in invalidationClasses
3. One or more of the element's children needed style recalc.

This patch addresses #1, but should not affect any other cases. In particular 

             for (InvalidationList::const_iterator it = invalidationList->begin(); it != invalidationList->end(); ++it) {
                 if ((*it)->wholeSubtreeInvalid()) {
@@ -396,8 +399,6 @@ bool RuleFeatureSet::invalidateStyleForClassChange(Element* element, Vector<Atom
         }
     }
 
-    bool thisElementNeedsStyleRecalc = false;
-
     if (element->hasClass()) {
         const SpaceSplitString& classNames = element->classNames();
         for (Vector<AtomicString>::const_iterator it = invalidationClasses.begin(); it != invalidationClasses.end(); ++it) {