Eliminate old style import from language tests

tests/language/prefix1_negative_test.dart

 // Copyright (c) 2011, 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.
 //
 
-#library("Prefix1NegativeTest.dart");
-#import("library1.dart");
+library Prefix1NegativeTest.dart;
+import "library1.dart";
 
 class Prefix1NegativeTest {
   static Main() {
     // This is a syntax error as library1 was not imported with a prefix.
     return library1.foo;
   }
 }
 
 main() {
   Prefix1NegativeTest.Main();
 }