Implemented method for printing invalidation sets.

Source/core/css/invalidation/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 56 matching lines @@
     void setTreeBoundaryCrossing() { m_treeBoundaryCrossing = true; }
     bool treeBoundaryCrossing() const { return m_treeBoundaryCrossing; }
 
     void setCustomPseudoInvalid() { m_customPseudoInvalid = true; }
     bool customPseudoInvalid() const { return m_customPseudoInvalid; }
 
     bool isEmpty() const { return !m_classes && !m_ids && !m_tagNames && !m_attributes; }
 
     void trace(Visitor*);
 
+#ifndef NDEBUG
+    void show() const;
+#endif
+
 private:
     DescendantInvalidationSet();
 
     WillBeHeapHashSet<AtomicString>& ensureClassSet();
     WillBeHeapHashSet<AtomicString>& ensureIdSet();
     WillBeHeapHashSet<AtomicString>& ensureTagNameSet();
     WillBeHeapHashSet<AtomicString>& ensureAttributeSet();
 
     // FIXME: optimize this if it becomes a memory issue.
     OwnPtrWillBeMember<WillBeHeapHashSet<AtomicString> > m_classes;
     OwnPtrWillBeMember<WillBeHeapHashSet<AtomicString> > m_ids;
     OwnPtrWillBeMember<WillBeHeapHashSet<AtomicString> > m_tagNames;
     OwnPtrWillBeMember<WillBeHeapHashSet<AtomicString> > m_attributes;
 
     // If true, all descendants might be invalidated, so a full subtree recalc is required.
     unsigned m_allDescendantsMightBeInvalid : 1;
 
     // If true, all descendants which are custom pseudo elements must be invalidated.
     unsigned m_customPseudoInvalid : 1;
 
     // If true, the invalidation must traverse into ShadowRoots with this set.
     unsigned m_treeBoundaryCrossing : 1;
 };
 
 } // namespace WebCore
 
 #endif // DescendantInvalidationSet_h