Add Isolate.onExit.

sdk/lib/_internal/lib/isolate_patch.dart

Index: sdk/lib/_internal/lib/isolate_patch.dart
diff --git a/sdk/lib/_internal/lib/isolate_patch.dart b/sdk/lib/_internal/lib/isolate_patch.dart
index 3858c159c137a456d0fe83ebdb149647d5a5a15f..8e6c6dd0ab3e5983505e2de0f3668d7e13081059 100644
--- a/sdk/lib/_internal/lib/isolate_patch.dart
+++ b/sdk/lib/_internal/lib/isolate_patch.dart
@@ -16,7 +16,7 @@ patch class Isolate {
                                      { bool paused: false }) {
     try {
       return IsolateNatives.spawnFunction(entryPoint, message, paused)
-          .then((msg) => new Isolate._fromControlPort(msg[1], msg[2]));
+          .then((msg) => new Isolate._fromControlPort(msg[1], msg[2], msg[3]));
     } catch (e, st) {
       return new Future<Isolate>.error(e, st);
     }
@@ -35,7 +35,7 @@ patch class Isolate {
         throw new ArgumentError("Args must be a list of Strings $args");
       }
       return IsolateNatives.spawnUri(uri, args, message, paused)
-          .then((msg) => new Isolate._fromControlPort(msg[1], msg[2]));
+          .then((msg) => new Isolate._fromControlPort(msg[1], msg[2], msg[3]));
     } catch (e, st) {
       return new Future<Isolate>.error(e, st);
     }