Revert "Build Observatory with runtime"

runtime/observatory/test/gc_test.dart

-// Copyright (c) 2014, 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.
-
-import 'package:observatory/service_io.dart';
-import 'test_helper.dart';
-
-import 'dart:async';
-
-void script() {
-  List<int> data;
-  var grow;
-  grow = (int iterations, int size, Duration duration) {
-    if (iterations <= 0) {
-      return;
-    }
-    data = new List<int>(size);
-    new Timer(duration, () => grow(iterations - 1, size, duration));
-  };
-  grow(100, 1 << 24, new Duration(seconds: 1));
-}
-
-var tests = [
-
-(Isolate isolate) {
-  Completer completer = new Completer();
-  // Expect at least this many GC events.
-  int gcCountdown = 3;
-  isolate.vm.events.stream.listen((ServiceEvent event) {
-    if (event.eventType == 'GC' && --gcCountdown == 0) {
-      completer.complete();
-    }
-  });
-  return completer.future;
-},
-
-];
-
-main(args) => runIsolateTests(args, tests, testeeConcurrent: script);