Revert "Unify dart:isolate."

lib/isolate/isolate_api.dart

Index: lib/isolate/isolate_api.dart
diff --git a/lib/isolate/base.dart b/lib/isolate/isolate_api.dart
similarity index 96%
rename from lib/isolate/base.dart
rename to lib/isolate/isolate_api.dart
index b5d92bfcd43e6c4df66ac5eb4e55c641f6c44b5f..010007e2b5bd63f8ae59a3420ec226f2593fa35c 100644
--- a/lib/isolate/base.dart
+++ b/lib/isolate/isolate_api.dart
@@ -14,7 +14,7 @@ class IsolateSpawnException implements Exception {
  * 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
@@ -32,7 +32,9 @@ external ReceivePort get 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
@@ -41,7 +43,9 @@ external SendPort spawnFunction(void topLevelFunction());
  *
  * 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
@@ -142,7 +146,3 @@ interface SendPortSync {
   callSync(var message);
 
 }
-
-class _ReceivePortFactory {
-  external factory ReceivePort();
-}