Retain elements a finer granularity than library.

dart/tests/compiler/dart2js/mirrors_used_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 the @MirrorsUsed annotation suppress hints and that only
 /// requested elements are retained for reflection.
 library dart2js.test.mirrors_used_test;
 
 import 'package:expect/expect.dart';
 
@@ skipping 30 matching lines @@
   for (var element in generatedCode) {
     print(element);
   }
   print('');
 
   // This assertion can fail for two reasons:
   // 1. Too many elements retained for reflection.
   // 2. Some code was refactored, and there are more methods.
   // Either situation could be problematic, but in situation 2, it is often
   // acceptable to increase [expectedMethodCount] a little.
-  int expectedMethodCount = 315;
+  int expectedMethodCount = 317;
   Expect.isTrue(
       generatedCode.length <= expectedMethodCount,
       'Too many compiled methods: '
       '${generatedCode.length} > $expectedMethodCount');
 
   for (var library in compiler.libraries.values) {
     library.forEachLocalMember((member) {
-      if (library == compiler.mainApp) {
-        // TODO(ahe): We currently retain the entire library. Update this test
-        // to test that only Foo is retained.
+      if (library == compiler.mainApp
+          && member.name == const SourceString('Foo')) {
         Expect.isTrue(
             compiler.backend.isNeededForReflection(member), '$member');
+        member.forEachLocalMember((classMember) {
+          Expect.isTrue(
+              compiler.backend.isNeededForReflection(classMember),
+              '$classMember');
+        });
       } else {
         Expect.isFalse(
             compiler.backend.isNeededForReflection(member), '$member');
       }
     });
   }
 }
 
 const MEMORY_SOURCE_FILES = const <String, String> {
   'main.dart': """
 @MirrorsUsed(targets: const [Foo], override: '*')
 import 'dart:mirrors';
 
 import 'library.dart';
 
-class Foo {}
+class Foo {
+  int field;
+  instanceMethod() {}
+  static staticMethod() {}
+}
+
+unusedFunction() {
+}
 
 main() {
   useReflect(Foo);
 }
 """,
   'library.dart': """
 library lib;
 
 import 'dart:mirrors';
 
 useReflect(type) {
   print(new Symbol('Foo'));
   print(MirrorSystem.getName(reflectClass(type).owner.qualifiedName));
 }
 """,
 };