Implement weak persistent handles in the Dart API.

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index b59ca99f21d3913e0b446898db01c995e8665c95..4bbb45a935c052ef3beea010b75db4c467231cc1 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -334,6 +334,13 @@ RawObject* Isolate::StandardRunLoop() {
 
 void Isolate::VisitObjectPointers(ObjectPointerVisitor* visitor,
                                   bool validate_frames) {
+  VisitStrongObjectPointers(visitor, validate_frames);
+  VisitWeakObjectPointers(visitor);
+}
+
+
+void Isolate::VisitStrongObjectPointers(ObjectPointerVisitor* visitor,
+                                        bool validate_frames) {
   ASSERT(visitor != NULL);
 
   // Visit objects in the object store.
@@ -355,7 +362,7 @@ void Isolate::VisitObjectPointers(ObjectPointerVisitor* visitor,
 
   // Visit the dart api state for all local and persistent handles.
   if (api_state() != NULL) {
-    api_state()->VisitObjectPointers(visitor);
+    api_state()->VisitStrongObjectPointers(visitor);
   }
 
   // Visit all objects in the code index table.
@@ -370,4 +377,11 @@ void Isolate::VisitObjectPointers(ObjectPointerVisitor* visitor,
   debugger()->VisitObjectPointers(visitor);
 }
 
+
+void Isolate::VisitWeakObjectPointers(ObjectPointerVisitor* visitor) {
+  if (api_state() != NULL) {
+    api_state()->VisitWeakObjectPointers(visitor);
+  }
+}
+
 }  // namespace dart