Use words please.

runtime/observatory/tests/service/mirror_references_test.dart

 // Copyright (c) 2014, 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=--compile-all --error_on_bad_type --error_on_bad_override
 
 library vm_references_test;
 
 import 'dart:mirrors';
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 
 class Foo { }
 
 Foo foo;
 var /*MirrorReference*/ ref;
 
 void script() {
   foo = new Foo();
   ClassMirror fooClassMirror = reflectClass(Foo);
   InstanceMirror fooClassMirrorMirror = reflect(fooClassMirror);
   LibraryMirror libmirrors = fooClassMirrorMirror.type.owner;
   ref = reflect(fooClassMirror).getField(MirrorSystem.getSymbol('_reflectee', libmirrors)).reflectee;
 }
 
 var tests = [
 
 (Isolate isolate) =>
-  isolate.rootLib.load().then((Library lib) {
+  isolate.rootLibrary.load().then((Library lib) {
     Field fooField = lib.variables.singleWhere((v) => v.name == 'foo');
     Instance foo = fooField.value;
     Field refField = lib.variables.singleWhere((v) => v.name == 'ref');
     Instance ref = refField.value;
 
     expect(foo.isMirrorReference, isFalse);
     expect(ref.isMirrorReference, isTrue);
     expect(ref.referent, isNull);
     return ref.load().then((Instance loadedRef) {
       expect(loadedRef.referent, isNotNull);
       expect(loadedRef.referent.name, equals('Foo'));
       expect(loadedRef.referent, equals(foo.clazz));
     });
   }),
 
 ];
 
 main(args) => runIsolateTests(args, tests, testeeBefore: script);