Implement weak persistent handles in the Dart API.

runtime/include/dart_api.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 INCLUDE_DART_API_H_
 #define INCLUDE_DART_API_H_
 
 /** \mainpage Dart Embedding API Reference
  *
  * Dart is a class-based programming language for creating structured
@@ skipping 186 matching lines @@
 DART_EXPORT Dart_Handle Dart_NewPersistentHandle(Dart_Handle object);
 
 /**
  * Deallocates a persistent handle.
  *
  * Requires there to be a current isolate.
  */
 DART_EXPORT void Dart_DeletePersistentHandle(Dart_Handle object);
 
 /**
- * Takes a persistent handle and makes it weak.
+ * Allocates a weak persistent handle for an object.
  *
- * UNIMPLEMENTED.
+ * This handle has the lifetime of the current isolate unless it is
+ * explicitly deallocated by calling Dart_DeletePersistentHandle.
  *
  * Requires there to be a current isolate.
  */
-DART_EXPORT Dart_Handle Dart_MakeWeakPersistentHandle(Dart_Handle object);
-// TODO(turnidge): Needs a "near death" callback here.
-// TODO(turnidge): Add IsWeak, Clear, etc.
+DART_EXPORT Dart_Handle Dart_NewWeakPersistentHandle(Dart_Handle object);
 
 /**
- * Takes a weak persistent handle and makes it non-weak.
- *
- * UNIMPLEMENTED.
+ * Is this object a weak persistent handle?
  *
  * Requires there to be a current isolate.
  */
-DART_EXPORT Dart_Handle Dart_MakePersistentHandle(Dart_Handle object);
+DART_EXPORT bool Dart_IsWeakPersistentHandle(Dart_Handle object);
 
 // --- Initialization and Globals ---
 
 /**
  * An isolate creation and initialization callback function.
  *
  * This callback, provided by the embedder, is called when an isolate needs
  * to be created. The callback should create an isolate and load the
  * required scripts for execution.
  *
@@ skipping 1150 matching lines @@
 
 // --- Profiling support ----
 
 // External pprof support for gathering and dumping symbolic
 // information that can be used for better profile reports for
 // dynamically generated code.
 DART_EXPORT void Dart_InitPprofSupport();
 DART_EXPORT void Dart_GetPprofSymbolInfo(void** buffer, int* buffer_size);
 
 #endif  // INCLUDE_DART_API_H_