Disallow heap objects containing unsafe on-heap iterators.

tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.h

 // Copyright 2016 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.
 
 #ifndef FIELDS_ILLEGAL_TRACING_H_
 #define FIELDS_ILLEGAL_TRACING_H_
 
 #include "heap/stubs.h"
 
 namespace blink {
@@ skipping 20 matching lines @@
 
 class PartObject {
     DISALLOW_NEW();
 public:
     void trace(Visitor*);
 private:
     OwnPtr<HeapObject> m_obj1;
     RefPtr<HeapObject> m_obj2;
     bar::unique_ptr<HeapObject> m_obj3;
     std::unique_ptr<HeapObject> m_obj4;
+    Vector<int>::iterator m_iterator1;
+    HeapVector<Member<HeapObject>>::iterator m_iterator2;
+    HeapHashSet<PartObject>::const_iterator m_iterator3;
 };
 
 class HeapObject : public GarbageCollectedFinalized<HeapObject> {
 public:
     void trace(Visitor*);
 private:
     PartObject m_part;
     OwnPtr<HeapObject> m_obj1;
     RefPtr<HeapObject> m_obj2;
     bar::unique_ptr<HeapObject> m_obj3;
     std::unique_ptr<HeapObject> m_obj4;
+    HeapHashMap<int, Member<HeapObject>>::reverse_iterator m_iterator3;
+    HeapDeque<Member<HeapObject>>::const_reverse_iterator m_iterator4;
+    HeapListHashSet<Member<HeapObject>>::const_iterator m_iterator5;
+    HeapLinkedHashSet<Member<HeapObject>>::const_iterator m_iterator6;
 };
 
 }
 
 #endif