BREAKING CHANGE: enforce part of directive

tests/language/generic_instanceof.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.
 // Test that instanceof works correctly with type variables.
 
+part of GenericInstanceofTest.dart;
+
 class Foo<T> {
   Foo() {}
 
   bool isT(x) { // Untyped parameter to ensure that the static type
                 // does not affect the result.
     return x is T;
   }
 
   bool isListT(x) {
     return x is List<T>;
@@ skipping 102 matching lines @@
     {
       Foo foo = new Foo<String>();
       Expect.equals(true, foo.isListT(new List(5)));
       Expect.equals(false, foo.isListT(new List<Object>(5)));
       Expect.equals(false, foo.isListT(new List<int>(5)));
       Expect.equals(false, foo.isListT(new List<num>(5)));
       Expect.equals(true, foo.isListT(new List<String>(5)));
     }
   }
 }