Free HashSets on setWholeSubtreeInvalid.

Source/core/css/analyzer/DescendantInvalidationSet.cpp

Index: Source/core/css/analyzer/DescendantInvalidationSet.cpp
diff --git a/Source/core/css/analyzer/DescendantInvalidationSet.cpp b/Source/core/css/analyzer/DescendantInvalidationSet.cpp
index 5cb3785b594df8aca99d704623511a94fe705e93..8a4aa57278870684f6b4efb9aa1152d748ea8673 100644
--- a/Source/core/css/analyzer/DescendantInvalidationSet.cpp
+++ b/Source/core/css/analyzer/DescendantInvalidationSet.cpp
@@ -43,11 +43,15 @@ DescendantInvalidationSet::DescendantInvalidationSet()
 
 void DescendantInvalidationSet::combine(const DescendantInvalidationSet& other)
 {
-    m_allDescendantsMightBeInvalid = m_allDescendantsMightBeInvalid || other.m_allDescendantsMightBeInvalid;
     // No longer bother combining data structures, since the whole subtree is deemed invalid.
-    if (m_allDescendantsMightBeInvalid)
+    if (wholeSubtreeInvalid())
         return;
 
+    if (other.wholeSubtreeInvalid()) {
+        setWholeSubtreeInvalid();
+        return;
+    }
+
     if (other.m_classes) {
         HashSet<AtomicString>::const_iterator end = other.m_classes->end();
         for (HashSet<AtomicString>::const_iterator it = other.m_classes->begin(); it != end; ++it)
@@ -90,20 +94,26 @@ HashSet<AtomicString>& DescendantInvalidationSet::ensureTagNameSet()
 
 void DescendantInvalidationSet::addClass(const AtomicString& className)
 {
+    if (wholeSubtreeInvalid())
+        return;
     ensureClassSet().add(className);
 }
 
 void DescendantInvalidationSet::addId(const AtomicString& id)
 {
+    if (wholeSubtreeInvalid())
+        return;
     ensureIdSet().add(id);
 }
 
 void DescendantInvalidationSet::addTagName(const AtomicString& tagName)
 {
+    if (wholeSubtreeInvalid())
+        return;
     ensureTagNameSet().add(tagName);
 }
 
-void DescendantInvalidationSet::getClasses(Vector<AtomicString>& classes)
+void DescendantInvalidationSet::getClasses(Vector<AtomicString>& classes) const
 {
     if (!m_classes)
         return;