Minor observatory test cleanups.

runtime/observatory/tests/service/pause_on_start_then_step_test.dart

 // Copyright (c) 2015, 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.
-// VMOptions=--compile_all --error_on_bad_type --error_on_bad_override
+// VMOptions=--error_on_bad_type --error_on_bad_override
 
 import 'package:observatory/service_io.dart';
-import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 import 'dart:async';
 
 void testMain() {
   print('Hello');
 }
 
 var tests = [
 
 (Isolate isolate) async {
@@ skipping 31 matching lines @@
 
   // Wait for the isolate to hit PauseBreakpoint.
   await completer.future;
 },
 
 ];
 
 main(args) => runIsolateTests(args, tests,
                               testeeConcurrent: testMain,
                               pause_on_start: true, pause_on_exit: true);