Use "package:" imports for pub.

test/serve/web_socket/path_to_urls_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS d.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 pub_tests;
 
 import 'package:path/path.dart' as p;
+import 'package:pub/src/io.dart';
 
-import '../../../lib/src/io.dart';
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 import '../utils.dart';
 
 main() {
   // TODO(rnystrom): Split into independent tests.
   initConfig();
   integration("pathToUrls converts asset ids to matching URL paths", () {
     d.dir("foo", [
       d.libPubspec("foo", "1.0.0"),
@@ skipping 105 matching lines @@
       "path": canonicalize(p.join(sandboxDir, "foo", "lib", "foo.dart"))
     }, {"urls": [
       getServerUrl("test", "packages/foo/foo.dart"),
       getServerUrl("web", "packages/foo/foo.dart"),
       getServerUrl("randomdir", "packages/foo/foo.dart")
     ]});
 
     endPubServe();
   });
 }