Thread the weak persistent handle free-list through the raw_ field.

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 88 matching lines @@
   PersistentHandle() { }
   ~PersistentHandle() { }
 
   // Overload the raw_ field as a next pointer when adding freed
   // handles to the free list.
   PersistentHandle* Next() {
     return reinterpret_cast<PersistentHandle*>(raw_);
   }
   void SetNext(PersistentHandle* free_list) {
     raw_ = reinterpret_cast<RawObject*>(free_list);
+    ASSERT(!raw_->IsHeapObject());
   }
   void FreeHandle(PersistentHandle* free_list) {
     SetNext(free_list);
   }
 
   RawObject* raw_;
   DISALLOW_ALLOCATION();  // Allocated through AllocateHandle methods.
   DISALLOW_COPY_AND_ASSIGN(PersistentHandle);
 };
 
@@ skipping 25 matching lines @@
       handle->Clear();
     }
   }
 
  private:
   friend class WeakPersistentHandles;
 
   WeakPersistentHandle() : raw_(NULL), peer_(NULL), callback_(NULL) { }
   ~WeakPersistentHandle() { }
 
-  // Overload the callback_ field as a next pointer when adding freed
+  // Overload the raw_ field as a next pointer when adding freed
   // handles to the free list.
   WeakPersistentHandle* Next() {
-    return reinterpret_cast<WeakPersistentHandle*>(callback_);
+    return reinterpret_cast<WeakPersistentHandle*>(raw_);
   }
   void SetNext(WeakPersistentHandle* free_list) {
-    callback_ = reinterpret_cast<Dart_WeakPersistentHandleFinalizer>(free_list);
+    raw_ = reinterpret_cast<RawObject*>(free_list);
+    ASSERT(!raw_->IsHeapObject());
   }
   void FreeHandle(WeakPersistentHandle* free_list) {
-    raw_ = NULL;
     SetNext(free_list);
   }
 
   void Clear() {
     raw_ = Object::null();
     peer_ = NULL;
     callback_ = NULL;
   }
 
   RawObject* raw_;
@@ skipping 384 matching lines @@
           ApiNativeScope::Current()->zone()->GetBaseZone()) {}
   ApiGrowableArray()
       : BaseGrowableArray<T, ValueObject>(
           ApiNativeScope::Current()->zone()->GetBaseZone()) {}
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DART_API_STATE_H_