Mirrors overhaul.

dart/tests/lib/mirrors/invoke_import_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.
 
 library test.invoke_import_test;
 
 import 'dart:mirrors';
 import 'package:expect/expect.dart';
 
 import 'other_library.dart';
 
 main() {
   LibraryMirror thisLibrary =
-      currentMirrorSystem().findLibrary(#test.invoke_import_test).single;
+      currentMirrorSystem().findLibrary(#test.invoke_import_test);
 
   Expect.throws(() => thisLibrary.invoke(#topLevelMethod, []),
                 (e) => e is NoSuchMethodError,
                 'Should not invoke imported method #topLevelMethod');
 
   Expect.throws(() => thisLibrary.getField(#topLevelGetter),
                 (e) => e is NoSuchMethodError,
                 'Should not invoke imported getter #topLevelGetter');
 
   Expect.throws(() => thisLibrary.getField(#topLevelField),
                 (e) => e is NoSuchMethodError,
                 'Should not invoke imported field #topLevelField');
 
   Expect.throws(() => thisLibrary.setField(#topLevelSetter, 23),
                 (e) => e is NoSuchMethodError,
                 'Should not invoke imported setter #topLevelSetter');
 
   Expect.throws(() => thisLibrary.setField(#topLevelField, 23),
                 (e) => e is NoSuchMethodError,
                 'Should not invoke imported field #topLevelField');
 }