Add missing pieces of my last CL

runtime/observatory/tests/service/set_library_debuggable_test.dart

 // Copyright (c) 2016, 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
 
 library set_library_debuggable_test;
 
 import 'dart:developer';
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'service_test_common.dart';
 import 'test_helper.dart';
 
 const LINE_A = 20;
 const LINE_B = 21;
 const LINE_C = 22;
 
 testMain() async {
   debugger();
   print('hi');   // LINE_A.
   print('yep');  // LINE_B.
   print('zoo');  // LINE_C.
 }
 
 var tests = [
+  hasStoppedAtBreakpoint,
+  markDartColonLibrariesDebuggable,
   (Isolate isolate) async {
     await isolate.reload();
     Library dartCore = isolate.libraries.firstWhere(
       (Library library) => library.uri == 'dart:core');
-    await dartCore.load();
+    await dartCore.reload();
     expect(dartCore.debuggable, equals(true));
   },
   stoppedInFunction('testMain', contains:true),
   stoppedAtLine(LINE_A),
   stepInto,
   stoppedInFunction('print'),
   stepOut,
   stoppedInFunction('testMain', contains:true),
   stoppedAtLine(LINE_B),
   (Isolate isolate) async {
@@ skipping 15 matching lines @@
     expect(dartCore.debuggable, equals(false));
   },
   stoppedInFunction('testMain', contains:true),
   stoppedAtLine(LINE_B),
   stepInto,
   stoppedInFunction('testMain', contains:true),
   stoppedAtLine(LINE_C),
 ];
 
 main(args) async => runIsolateTests(args, tests, testeeConcurrent: testMain);