Implement prologue weak persistent handles.

runtime/vm/dart_api_impl.h

 // Copyright (c) 2011, 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_IMPL_H_
 #define VM_DART_API_IMPL_H_
 
 #include "vm/allocation.h"
 #include "vm/object.h"
 
 namespace dart {
 
 class ApiState;
+class FinalizablePersistentHandle;
 class LocalHandle;
 class PersistentHandle;
-class WeakPersistentHandle;
 
 const char* CanonicalFunction(const char* func);
 
 #define CURRENT_FUNC CanonicalFunction(__FUNCTION__)
 
 // Checks that the current isolate is not NULL.
 #define CHECK_ISOLATE(isolate)                                                \
   do {                                                                        \
     if ((isolate) == NULL) {                                                  \
       FATAL1("%s expects there to be a current isolate. Did you "             \
@@ skipping 60 matching lines @@
 
   // Validates and converts the passed in handle as a local handle.
   static LocalHandle* UnwrapAsLocalHandle(const ApiState& state,
                                           Dart_Handle object);
 
   // Validates and converts the passed in handle as a persistent handle.
   static PersistentHandle* UnwrapAsPersistentHandle(const ApiState& state,
                                                     Dart_Handle object);
 
   // Validates and converts the passed in handle as a weak persistent handle.
-  static WeakPersistentHandle* UnwrapAsWeakPersistentHandle(
+  static FinalizablePersistentHandle* UnwrapAsWeakPersistentHandle(
       const ApiState& state,
       Dart_Handle object);
 
+  // Validates and converts the passed in handle as a prologue weak
+  // persistent handle.
+  static FinalizablePersistentHandle* UnwrapAsPrologueWeakPersistentHandle(
+      const ApiState& state,
+      Dart_Handle object);
+
   // Casts the internal Isolate* type to the external Dart_Isolate type.
   static Dart_Isolate CastIsolate(Isolate* isolate);
 
   // Gets the handle used to designate successful return.
   static Dart_Handle Success();
 
   // Generates a handle used to designate an error return.
   static Dart_Handle NewError(const char* format, ...);
 
   // Gets a handle to Null.
@@ skipping 32 matching lines @@
   }
  private:
   Isolate* saved_isolate_;
 
   DISALLOW_COPY_AND_ASSIGN(IsolateSaver);
 };
 
 }  // namespace dart.
 
 #endif  // VM_DART_API_IMPL_H_