Add test for expected source mappings

tests/compiler/dart2js/inference/inference_test_helper.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.
 
 import 'package:compiler/src/common.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/elements/elements.dart';
 import 'package:compiler/src/resolution/tree_elements.dart';
 import 'package:compiler/src/tree/nodes.dart';
 import 'package:compiler/src/types/types.dart';
 import 'package:expect/expect.dart';
 
 import '../annotated_code_helper.dart';
 import '../memory_compiler.dart';
 import 'enumerator.dart';
 
 checkCode(String annotatedCode) async {
-  AnnotatedCode code = new AnnotatedCode(annotatedCode);
+  AnnotatedCode code = new AnnotatedCode.fromText(annotatedCode);
   Map<Id, String> expectedMap = computeExpectedMap(code);
   Compiler compiler =
       compilerFor(memorySourceFiles: {'main.dart': code.sourceCode});
   compiler.stopAfterTypeInference = true;
   Uri mainUri = Uri.parse('memory:main.dart');
   await compiler.run(mainUri);
   compiler.mainApp.forEachLocalMember((member) {
     if (member.isFunction) {
       checkMember(compiler, expectedMap, member);
     } else if (member.isClass) {
@@ skipping 68 matching lines @@
   visitSend(Send node) {
     checkSend(node);
     visitNode(node);
   }
 
   visitSendSet(SendSet node) {
     checkSend(node);
     visitNode(node);
   }
 }