Rename new Uri.fromString to Uri.parse.

tests/standalone/io/regress_6521_test.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.
 //
 // Regression test for http://code.google.com/p/dart/issues/detail?id=6393.
 
 import "dart:io";
 import "dart:uri";
 
 var client = new HttpClient();
 var clientRequest;
 
 void main() {
   var server = new HttpServer();
   server.listen("127.0.0.1", 0);
   server.defaultRequestHandler = (req, rsp) {
     req.inputStream.onData = () {
       req.inputStream.read();
       rsp.outputStream.close();
     };
   };
 
   var connection = client.openUrl(
       "POST",
-      new Uri.fromString("http://localhost:${server.port}/"));
+      Uri.parse("http://localhost:${server.port}/"));
   connection.onRequest = (request) {
     // Keep a reference to the client request object.
     clientRequest = request;
     request.outputStream.write([0]);
   };
   connection.onResponse = (response) {
     response.inputStream.onClosed = () {
       // Wait with closing the client request until the response is done.
       clientRequest.outputStream.close();
       client.shutdown();
       server.close();
     };
   };
 }