Refactor the dart api a bit:

runtime/vm/dart_api_state.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_STATE_H_
 #define VM_DART_API_STATE_H_
 
 #include "include/dart_api.h"
 
 #include "vm/dart_api_impl.h"
@@ skipping 66 matching lines @@
 class PersistentHandle {
  public:
   enum {
     StrongReference = 0,
     WeakReference,
   };
 
   // Accessors.
   RawObject* raw() const { return raw_; }
   void set_raw(const LocalHandle& ref) { raw_ = ref.raw(); }
+  void set_raw(const Object& object) { raw_ = object.raw(); }
   static intptr_t raw_offset() { return OFFSET_OF(PersistentHandle, raw_); }
   void* callback() const { return callback_; }
   void set_callback(void* value) { callback_ = value; }
   intptr_t type() const { return type_; }
   void set_type(intptr_t value) { type_ = value; }
 
+ private:
+  friend class PersistentHandles;
+
+  PersistentHandle() { }
+  ~PersistentHandle() { }
+
   // Overload the callback_ field as a next pointer when adding freed
   // handles to the free list.
   PersistentHandle* Next() {
     return reinterpret_cast<PersistentHandle*>(callback_);
   }
   void SetNext(PersistentHandle* free_list) {
     callback_ = reinterpret_cast<void*>(free_list);
   }
   void FreeHandle(PersistentHandle* free_list) {
     raw_ = NULL;
     SetNext(free_list);
   }
 
- private:
-  PersistentHandle() { }
-  ~PersistentHandle() { }
-
   RawObject* raw_;
   void* callback_;
   intptr_t type_;
   DISALLOW_ALLOCATION();  // Allocated through AllocateHandle methods.
   DISALLOW_COPY_AND_ASSIGN(PersistentHandle);
 };
 
 
 // Local handles repository structure.
 static const int kLocalHandleSizeInWords = sizeof(LocalHandle) / kWordSize;
@@ skipping 74 matching lines @@
       handle = free_list_;
       free_list_ = handle->Next();
     } else {
       handle = reinterpret_cast<PersistentHandle*>(AllocateScopedHandle());
     }
     handle->set_callback(NULL);
     handle->set_type(PersistentHandle::StrongReference);
     return handle;
   }
 
+  void FreeHandle(PersistentHandle* handle) {
+    handle->FreeHandle(free_list());
+    set_free_list(handle);
+  }
+
   // Validate if passed in handle is a Persistent Handle.
   bool IsValidHandle(Dart_Handle object) const {
     return IsValidScopedHandle(reinterpret_cast<uword>(object));
   }
 
   // Returns a count of active handles (used for testing purposes).
   int CountHandles() const {
     return CountScopedHandles();
   }
 
@@ skipping 28 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(ApiLocalScope);
 };
 
 
 // Implementation of the API State used in dart api for maintaining
 // local scopes, persistent handles etc. These are setup on a per isolate
 // basis and destroyed when the isolate is shutdown.
 class ApiState {
  public:
-  ApiState() : top_scope_(NULL) { }
+  ApiState() : top_scope_(NULL), true_(NULL) { }
   ~ApiState() {
     while (top_scope_ != NULL) {
       ApiLocalScope* scope = top_scope_;
       top_scope_ = top_scope_->previous();
       delete scope;
     }
+    if (true_ != NULL) {
+      persistent_handles().FreeHandle(true_);
+      true_ = NULL;
+    }
   }
 
   // Accessors.
   ApiLocalScope* top_scope() const { return top_scope_; }
   void set_top_scope(ApiLocalScope* value) { top_scope_ = value; }
   PersistentHandles& persistent_handles() { return persistent_handles_; }
 
   void UnwindScopes(uword sp) {
     while (top_scope_ != NULL && top_scope_->stack_marker() < sp) {
       ApiLocalScope* scope = top_scope_;
@@ skipping 39 matching lines @@
   }
   int ZoneSizeInBytes() const {
     int total = 0;
     ApiLocalScope* scope = top_scope_;
     while (scope != NULL) {
       total += scope->zone().SizeInBytes();
       scope = scope->previous();
     }
     return total;
   }
+  PersistentHandle* True() {
+    if (true_ == NULL) {
+      Zone zone;  // Setup a VM zone as we are creating some handles.
+      HandleScope scope;  // Setup a VM handle scope.
+
+      const Object& true_object = Object::Handle(Bool::True());
+      true_ = persistent_handles().AllocateHandle();
+      true_->set_raw(true_object);
+    }
+    return true_;
+  }
 
  private:
   PersistentHandles persistent_handles_;
   ApiLocalScope* top_scope_;
 
+  // A persistent handle to the "True" object.
+  PersistentHandle* true_;
+
   DISALLOW_COPY_AND_ASSIGN(ApiState);
 };
 
 }  // namespace dart
 
 #endif  // VM_DART_API_STATE_H_