Fix language tests wrt. warnings.

tests/language/crash_6725_part.dart

 // Copyright (c) 2013, 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.
 
 // Regression test for a crash in dart2js.
 
+part of crash_6725;
+
 class Fisk {
   it1(x) {
     // "key" is unresolved and caused a crash in dart2js.
     // This is the original example the user reported.
     for (key in x) {
       print(key);
     }
   }
 
   it2(x) {
@@ skipping 11 matching lines @@
     }
   }
 }
 
 class SubFisk extends Fisk {
   var key;
   var length;
   var fisk;
 }
 
-main() {
+test() {
   Fisk f = new SubFisk();
   var m = (x) {
     for (undeclared in x) {
       print(undeclared);
     }
   };
   if (new DateTime.now().millisecondsSinceEpoch == 42) {
     f = null;
     m = (x) {};
   }
@@ skipping 13 matching lines @@
     throw 'f.fisk != 42 (${f.fisk})';
   }
 
   try {
     m([87, 42]);
     throw 'NoSuchMethodError expected';
   } on NoSuchMethodError {
     // Expected.
   }
 }