Global cycle detection analysis.

tools/clang/blink_gc_plugin/tests/cycle_super.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "pure_virtual_trace.h"
+#include "cycle_super.h"
 
 namespace WebCore {
 
+void A::trace(Visitor* visitor) {
+    visitor->trace(m_d);
+}
+
+void B::trace(Visitor* visitor) {
+    A::trace(visitor);
+}
+
 void C::trace(Visitor* visitor) {
-    visitor->trace(m_a);
-    // Is not required to trace base classes B and A.
+    B::trace(visitor);
 }
 
 }