Add missing pieces of my last CL

runtime/observatory/tests/service/service_test_common.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.
 
 library service_test_common;
 
 import 'dart:async';
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/service_common.dart';
 import 'package:unittest/unittest.dart';
@@ skipping 188 matching lines @@
 }
 
 Future<Isolate> hasStoppedAtExit(Isolate isolate) {
   return hasPausedFor(isolate, ServiceEvent.kPauseExit);
 }
 
 Future<Isolate> hasPausedAtStart(Isolate isolate) {
   return hasPausedFor(isolate, ServiceEvent.kPauseStart);
 }
 
+Future<Isolate> markDartColonLibrariesDebuggable(Isolate isolate) async {
+  await isolate.reload();
+  for (Library lib in isolate.libraries) {
+    await lib.load();
+    if (lib.uri.startsWith('dart:') &&
+        !lib.uri.startsWith('dart:_')) {
+      var setDebugParams = {
+            'libraryId': lib.id,
+            'isDebuggable': true,
+          };
+      Map<String, dynamic> result =
+          await isolate.invokeRpcNoUpgrade('setLibraryDebuggable',
+                                           setDebugParams);
+    }
+  }
+  return isolate;
+}
+
 IsolateTest reloadSources([bool pause = false]) {
     return (Isolate isolate) async {
       Map<String, dynamic> params = <String, dynamic>{ };
       if (pause == true) {
         params['pause'] = pause;
       }
       return isolate.invokeRpc('reloadSources', params);
     };
 }
 
@@ skipping 153 matching lines @@
 
 Future<Instance> rootLibraryFieldValue(Isolate isolate,
                                        String fieldName) async {
   Library rootLib = await isolate.rootLibrary.load();
   Field field = rootLib.variables.singleWhere((v) => v.name == fieldName);
   await field.load();
   Instance value = field.staticValue;
   await value.load();
   return value;
 }