Disallow heap objects containing unsafe on-heap iterators.

tools/clang/blink_gc_plugin/Edge.cpp

Index: tools/clang/blink_gc_plugin/Edge.cpp
diff --git a/tools/clang/blink_gc_plugin/Edge.cpp b/tools/clang/blink_gc_plugin/Edge.cpp
index 77c6cfec4ba9013dd0988075a4093d851471d571..428e74749b773f4f9bf3c078536978be9b0f7df6 100644
--- a/tools/clang/blink_gc_plugin/Edge.cpp
+++ b/tools/clang/blink_gc_plugin/Edge.cpp
@@ -23,6 +23,7 @@ void RecursiveEdgeVisitor::AtWeakMember(WeakMember*) {}
 void RecursiveEdgeVisitor::AtPersistent(Persistent*) {}
 void RecursiveEdgeVisitor::AtCrossThreadPersistent(CrossThreadPersistent*) {}
 void RecursiveEdgeVisitor::AtCollection(Collection*) {}
+void RecursiveEdgeVisitor::AtIterator(Iterator*) {}
 
 void RecursiveEdgeVisitor::VisitValue(Value* e) {
   AtValue(e);
@@ -90,3 +91,7 @@ void RecursiveEdgeVisitor::VisitCollection(Collection* e) {
   e->AcceptMembers(this);
   Leave();
 }
+
+void RecursiveEdgeVisitor::VisitIterator(Iterator* e) {
+  AtIterator(e);
+}