Properly resolve top-level setters

tests/language/getter_setter_in_lib_test.dart

Index: tests/language/getter_setter_in_lib_test.dart
===================================================================
--- tests/language/getter_setter_in_lib_test.dart	(revision 45315)
+++ tests/language/getter_setter_in_lib_test.dart	(working copy)
@@ -5,9 +5,19 @@
 library GetterSetterInLibTest;
 import "package:expect/expect.dart";
 import 'getter_setter_in_lib.dart';
+import 'getter_setter_in_lib2.dart';
+import 'getter_setter_in_lib3.dart' as L3;
 
 main() {
   Expect.equals(42, foo);
   foo = 43;
   Expect.equals(42, foo);
+
+  Expect.equals(77, bar);
+  bar = 43;
+  Expect.equals(77, bar);
+
+  Expect.equals(L3.bar, 33);
+  L3.bar = 44;
+  Expect.equals(L3.bar, 44);
 }