1. Provide a framework to traverse persistent prolog weak handles.

runtime/vm/dart_api_state.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_DART_API_STATE_H_
 #define VM_DART_API_STATE_H_
 
 #include "include/dart_api.h"
 
 #include "platform/thread.h"
@@ skipping 740 matching lines @@
   }
 
   void VisitWeakHandles(HandleVisitor* visitor,
                         bool visit_prologue_weak_handles) {
     weak_persistent_handles().VisitHandles(visitor);
     if (visit_prologue_weak_handles) {
       prologue_weak_persistent_handles().VisitHandles(visitor);
     }
   }
 
+  void VisitPrologueWeakHandles(HandleVisitor* visitor) {
+    prologue_weak_persistent_handles().VisitHandles(visitor);
+  }
+
   bool IsValidLocalHandle(Dart_Handle object) const {
     ApiLocalScope* scope = top_scope_;
     while (scope != NULL) {
       if (scope->local_handles()->IsValidHandle(object)) {
         return true;
       }
       scope = scope->previous();
     }
     return false;
   }
@@ skipping 111 matching lines @@
           ApiNativeScope::Current()->zone()) {}
   ApiGrowableArray()
       : BaseGrowableArray<T, ValueObject>(
           ApiNativeScope::Current()->zone()) {}
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DART_API_STATE_H_