Free HashSets on setWholeSubtreeInvalid.

Source/core/css/analyzer/DescendantInvalidationSet.h

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 40 matching lines @@
         return adoptRef(new DescendantInvalidationSet);
     }
 
     void combine(const DescendantInvalidationSet& other);
 
     void addClass(const AtomicString& className);
     void addId(const AtomicString& id);
     void addTagName(const AtomicString& tagName);
 
     // Appends the classes in this DescendantInvalidationSet to the vector.
-    void getClasses(Vector<AtomicString>& classes);
+    void getClasses(Vector<AtomicString>& classes) const;
 
-    void setWholeSubtreeInvalid() { m_allDescendantsMightBeInvalid = true; };
-    bool wholeSubtreeInvalid() { return m_allDescendantsMightBeInvalid; }
+    void setWholeSubtreeInvalid();
+    bool wholeSubtreeInvalid() const { return m_allDescendantsMightBeInvalid; }
 private:
     DescendantInvalidationSet();
 
     HashSet<AtomicString>& ensureClassSet();
     HashSet<AtomicString>& ensureIdSet();
     HashSet<AtomicString>& ensureTagNameSet();
 
-    bool invalidateElementSubtreeInternal(Element*);
     // If true, all descendants might be invalidated, so a full subtree recalc is required.
     bool m_allDescendantsMightBeInvalid;
 
     // FIXME: optimize this if it becomes a memory issue.
     OwnPtr<HashSet<AtomicString> > m_classes;
     OwnPtr<HashSet<AtomicString> > m_ids;
     OwnPtr<HashSet<AtomicString> > m_tagNames;
 };
 
+inline void DescendantInvalidationSet::setWholeSubtreeInvalid()

[ojan, 2014/02/25 00:30:53]

Did you actually see performance difference in making this inline or just
keeping it inline because it used to be so before? If the former, LGTM. If the
latter, I'd prefer that this be moved to the cpp file and not inlined. 

[rune, 2014/02/25 08:36:17]

https://codereview.chromium.org/179483002/

+{
+    if (m_allDescendantsMightBeInvalid)
+        return;
+
+    m_allDescendantsMightBeInvalid = true;
+    m_classes = nullptr;
+    m_ids = nullptr;
+    m_tagNames = nullptr;
+}
+
 } // namespace WebCore
 
 #endif // DescendantInvalidationSet_h