Add #library to make test run properly under DRT.

tests/utils/src/Utf8Test.dart

 // Copyright (c) 2012, 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('Utf8Test');
 #import('dart:utf');
 
 String decode(List<int> bytes) => decodeUtf8(bytes);
 
 bool isRunningOnJavaScript() => 1 === 1.0;
 
 main() {
   // Google favorite: "Îñţérñåţîöñåļîžåţîờñ".
   String string = decode([0xc3, 0x8e, 0xc3, 0xb1, 0xc5, 0xa3, 0xc3, 0xa9, 0x72,
                           0xc3, 0xb1, 0xc3, 0xa5, 0xc5, 0xa3, 0xc3, 0xae, 0xc3,
@@ skipping 25 matching lines @@
     // DESERET CAPITAL LETTER BEE, unicode 0x10412(0xD801+0xDC12)
     // UTF-8: F0 90 90 92
     string = decode([0xf0, 0x90, 0x90, 0x92]);
     Expect.stringEquals("𐐒", string);
   } else {
     print('Skipping non-BMP character test');
   }
 
   // TODO(ahe): Add tests of bad input.
 }