Revert "Unify dart:isolate."

lib/isolate/isolate_api.dart

 // 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.
 
 class IsolateSpawnException implements Exception {
   const IsolateSpawnException(String this._s);
   String toString() => "IsolateSpawnException: '$_s'";
   final String _s;
 }
 
 /**
  * The initial [ReceivePort] available by default for this isolate. This
  * [ReceivePort] is created automatically and it is commonly used to establish
  * the first communication between isolates (see [spawnFunction] and
  * [spawnUri]).
  */
-external ReceivePort get port();
+ReceivePort get port() => _port;
 
 /**
  * Creates and spawns an isolate that shares the same code as the current
  * isolate, but that starts from [topLevelFunction]. The [topLevelFunction]
  * argument must be a static top-level function or a static method that takes no
  * arguments. It is illegal to pass a function closure.
  *
  * When any isolate starts (even the main script of the application), a default
  * [ReceivePort] is created for it. This port is available from the top-level
  * getter [port] defined in this library.
  *
  * [spawnFunction] returns a [SendPort] derived from the child isolate's default
  * port.
  *
  * See comments at the top of this library for more details.
  */
 // Note this feature is not yet available in the dartvm.
-external SendPort spawnFunction(void topLevelFunction());
+SendPort spawnFunction(void topLevelFunction()) {
+  return _spawnFunction(topLevelFunction);
+}
 
 /**
  * Creates and spawns an isolate whose code is available at [uri].  Like with
  * [spawnFunction], the child isolate will have a default [ReceivePort], and a
  * this function returns a [SendPort] derived from it.
  *
  * See comments at the top of this library for more details.
  */
-external SendPort spawnUri(String uri);
+SendPort spawnUri(String uri) {
+  return _spawnUri(uri);
+}
 
 /**
  * [SendPort]s are created from [ReceivePort]s. Any message sent through
  * a [SendPort] is delivered to its respective [ReceivePort]. There might be
  * many [SendPort]s for the same [ReceivePort].
  *
  * [SendPort]s can be transmitted to other isolates.
  */
 interface SendPort extends Hashable {
 
@@ skipping 80 matching lines @@
   SendPort toSendPort();
 
 }
 
 // TODO(kasperl): Make this hashable and document it.
 interface SendPortSync {
 
   callSync(var message);
 
 }
-
-class _ReceivePortFactory {
-  external factory ReceivePort();
-}