Disallow heap objects containing unsafe on-heap iterators.

tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.h

Index: tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.h
diff --git a/tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.h b/tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.h
index 7700b828d84e776d34b42417356514f3fb98cf52..f4d91dd274247b6bfd4e3269b5bb7b01adaf17e6 100644
--- a/tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.h
+++ b/tools/clang/blink_gc_plugin/tests/fields_illegal_tracing.h
@@ -38,6 +38,9 @@ private:
     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> {
@@ -49,6 +52,10 @@ private:
     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;
 };
 
 }