Remove deprecated Strings class.

utils/testrunner/pipeline_utils.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.
 
 part of pipeline;
 
 List stdout, stderr, log;
 var replyPort;
 int _procId = 1;
 Map _procs = {};
@@ skipping 43 matching lines @@
  * to the [Process] will be put in a map with key [procId]; in this case
  * the process can be terminated later by calling [stopProcess] and
  * passing in the [procId].
  * [outputMonitor] is an optional function that will be called back with each
  * line of output from the process.
  * Returns a [Future] for when the process terminates.
  */
 Future _processHelper(String command, List<String> args,
     [int timeout = 300, int procId = 0, Function outputMonitor]) {
   var completer = procId == 0 ? new Completer() : null;
-  log.add('Running $command ${Strings.join(args, " ")}');
+  log.add('Running $command ${args.join(" ")}');
   var timer = null;
   var stdoutHandler, stderrHandler;
   var processFuture = Process.start(command, args);
   processFuture.then((process) {
     _procs[procId] = process;
 
     timer = new Timer(new Duration(seconds: timeout), () {
       timer = null;
       process.kill();
     });
@@ skipping 104 matching lines @@
   stderr = new List();
   log = new List();
 }
 
 void completePipeline([exitCode = 0]) {
   replyPort.send([stdout, stderr, log, exitCode]);
 }
 
 /** Utility function to log diagnostic messages. */
 void logMessage(msg) => log.add(msg);