Revert "Parts must start with 'part of'" and "Attempt to fix VM build"

dart/tests/language/prefix3_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.
 //
 
 // Using the same prefix name while importing two different libraries is
 // not an error but both library1.dart and library2.dart define 'foo' which
 // results in a duplicate definition error.
 
-library Prefix3NegativeTest;
-import "library1.dart" as lib2;  // defines 'foo'.
-import "library2.dart" as lib2;  // also defines 'foo'.
+#library("Prefix3NegativeTest.dart");
+#import("library1.dart", prefix: "lib2");  // defines 'foo'.
+#import("library2.dart", prefix: "lib2");  // also defines 'foo'.
 
 
 main() {
   lib2.foo = 1;
 }