Mirrors overhaul.

dart/tests/compiler/dart2js_extra/mirror_type_inference_field2_test.dart

 // Copyright (c) 2013, 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.
 
 // Test that type inference sees the possible modification of `fisk` from
 // the mirror system and not infers the value to be an integer, or any
 // other elements that use `fisk` like `otherFisk` to be of type integer.
 library test;
 
 @MirrorsUsed(targets: 'fisk', override: '*')
 import 'dart:mirrors';
 
 import 'package:expect/expect.dart';
 
 var fisk = 1;
 var otherFisk = 42;
 
 main() {
-  var lm = currentMirrorSystem().findLibrary(const Symbol('test')).single;
+  var lm = currentMirrorSystem().findLibrary(const Symbol('test'));
   lm.setField(const Symbol('fisk'), 'hest');
   otherFisk = fisk;
   Expect.isTrue(otherFisk is String);
 }