Eliminate old style import from language tests

tests/language/library5_test.dart

Index: tests/language/library5_test.dart
===================================================================
--- tests/language/library5_test.dart	(revision 15598)
+++ tests/language/library5_test.dart	(working copy)
@@ -3,9 +3,9 @@
 // BSD-style license that can be found in the LICENSE file.
 //
 
-#library("Library5Test.dart");
-#import("library5a.dart", prefix : "lib5a");
-#import("library5b.dart", prefix : "lib5b");
+library Library5Test.dart;
+import "library5a.dart" as lib5a;
+import "library5b.dart" as lib5b;
 
 int foo(lib5a.Fun f) {
   return f();