Retain elements a finer granularity than library.

dart/tests/compiler/dart2js/mirrors_used_test.dart

Index: dart/tests/compiler/dart2js/mirrors_used_test.dart
diff --git a/dart/tests/compiler/dart2js/mirrors_used_test.dart b/dart/tests/compiler/dart2js/mirrors_used_test.dart
index 09fdd29c9b883a28848d4f775b1914e9865e1c14..f3719a5cdc3353b294c976bc46c93e478eb3b18f 100644
--- a/dart/tests/compiler/dart2js/mirrors_used_test.dart
+++ b/dart/tests/compiler/dart2js/mirrors_used_test.dart
@@ -48,7 +48,7 @@ void main() {
   // 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: '
@@ -56,11 +56,15 @@ void main() {
 
   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');
@@ -76,7 +80,14 @@ import 'dart:mirrors';
 
 import 'library.dart';
 
-class Foo {}
+class Foo {
+  int field;
+  instanceMethod() {}
+  static staticMethod() {}
+}
+
+unusedFunction() {
+}
 
 main() {
   useReflect(Foo);