Blink GC plugin: disallow GC derived types as part-object fields.

tools/clang/blink_gc_plugin/tests/part_object_to_gc_derived_class.h

Index: tools/clang/blink_gc_plugin/tests/part_object_to_gc_derived_class.h
diff --git a/tools/clang/blink_gc_plugin/tests/destructor_in_nonfinalized_class.h b/tools/clang/blink_gc_plugin/tests/part_object_to_gc_derived_class.h
similarity index 58%
copy from tools/clang/blink_gc_plugin/tests/destructor_in_nonfinalized_class.h
copy to tools/clang/blink_gc_plugin/tests/part_object_to_gc_derived_class.h
index 0e1c81516ce8ed9d986bb220cb9536225f14a417..ad5850248bf786bb576d7bce82f2ad4bd60855f1 100644
--- a/tools/clang/blink_gc_plugin/tests/destructor_in_nonfinalized_class.h
+++ b/tools/clang/blink_gc_plugin/tests/part_object_to_gc_derived_class.h
@@ -2,19 +2,20 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef DESTRUCTOR_IN_NONFINALIZED_CLASS_H_
-#define DESTRUCTOR_IN_NONFINALIZED_CLASS_H_
+#ifndef PART_OBJECT_TO_GC_DERIVED_CLASS_H_
+#define PART_OBJECT_TO_GC_DERIVED_CLASS_H_
 
 #include "heap/stubs.h"
 
 namespace WebCore {
 
-class HeapObject : public GarbageCollected<HeapObject> {
+class A : public GarbageCollected<A> { };
+
+class B : public GarbageCollected<B> {
 public:
-    ~HeapObject();
     void trace(Visitor*);
 private:
-    Member<HeapObject> m_obj;
+    A m_a;
 };
 
 }