Expose the new _getSourceReport api in the service protocol.

runtime/observatory/tests/service/coverage_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
 
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 import 'dart:developer';
 
 int globalVar = 100;
 
 class MyClass {
-       static       void myFunction(int value) {
+  static void myFunction(int value) {
     if (value < 0) {
       print("negative");
     } else {
       print("positive");
     }
     debugger();
   }
 
   static void otherFunction(int value) {
     if (value < 0) {
@@ skipping 71 matching lines @@
 
   // Isolate
   coverage = await isolate.invokeRpcNoUpgrade('_getCoverage', {});
   expect(coverage['type'], equals('CodeCoverage'));
   expect(coverage['coverage'].length, greaterThan(100));
 },
 
 ];
 
 main(args) => runIsolateTests(args, tests, testeeConcurrent: testFunction);