Refactor service tests in preparation of running on sky_shell

runtime/observatory/tests/service/break_on_function_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=--error_on_bad_type --error_on_bad_override  --verbose_debug
 
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
+import 'service_test_common.dart';
 import 'test_helper.dart';
 import 'dart:developer';
 
-testFunction(flag) {  // Line 11
+const int LINE_A = 14;
+
+testFunction(flag) {  // Line A.
   if (flag) {
     print("Yes");
   } else {
     print("No");
   }
 }
 
 testMain() {
   debugger();
   testFunction(true);
@@ skipping 11 matching lines @@
   var function = rootLib.functions.singleWhere((f) => f.name == 'testFunction');
 
   var bpt = await isolate.addBreakpointAtEntry(function);
   expect(bpt is Breakpoint, isTrue);
   print(bpt);
 },
 
 resumeIsolate,
 
 hasStoppedAtBreakpoint,
-stoppedAtLine(11),
+stoppedAtLine(LINE_A),
 resumeIsolate,
 
 hasStoppedAtBreakpoint,
-stoppedAtLine(11),
+stoppedAtLine(LINE_A),
 resumeIsolate,
 
 ];
 
 main(args) => runIsolateTests(args, tests, testeeConcurrent: testMain);