Partially implement LibraryMirror.topLevelMembers.

tests/lib/mirrors/synthetic_accessor_properties_test.dart

Index: tests/lib/mirrors/synthetic_accessor_properties_test.dart
diff --git a/tests/lib/mirrors/synthetic_accessor_properties_test.dart b/tests/lib/mirrors/synthetic_accessor_properties_test.dart
index fc96b6d6c667b6df002c63c2837476ee03d28c40..215d3a30a8e6a56a3309b723c36a04afb3157600 100644
--- a/tests/lib/mirrors/synthetic_accessor_properties_test.dart
+++ b/tests/lib/mirrors/synthetic_accessor_properties_test.dart
@@ -68,7 +68,6 @@ main() {
   mm = cm.staticMembers[const Symbol('finalStaticField=')];
   Expect.isNull(mm);
 
-  return;  /// 01: ok
 
   mm = lm.topLevelMembers[#topLevelField];
   expect('Method(s(topLevelField) in s(test.synthetic_accessor_properties),'
@@ -93,6 +92,8 @@ main() {
   mm = lm.topLevelMembers[const Symbol('finalTopLevelField=')];
   Expect.isNull(mm);
 
+  return;  /// 01: ok
+
   mm = lm.topLevelMembers[#C];
   expect('Method(s(C) in s(test.synthetic_accessor_properties),'
          ' top-level, synthetic, static, getter)', mm);