Address observatory analysis issues.

runtime/observatory/tests/service/evaluate_with_scope_test.dart

 // Copyright (c) 2017, 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=--error_on_bad_type --error_on_bad_override
 
-import 'dart:async';
-import 'dart:developer';
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
-import 'service_test_common.dart';
+
 import 'test_helper.dart';
 
 var thing1;
 var thing2;
 
 testeeMain() {
   thing1 = 3;
   thing2 = 4;
 }
 
@@ skipping 30 matching lines @@
       print(result);
     } catch (e) {
       didThrow = true;
       expect(e.toString(), contains("invalid 'scope' parameter"));
     }
     expect(didThrow, isTrue);
   },
 ];
 
 main(args) => runIsolateTests(args, tests, testeeBefore: testeeMain);