Second round of cleanups for new optional parameter semantics.

utils/pub/git.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.
 
 /**
  * Helper functionality for invoking Git.
  */
 library git;
 
 import 'io.dart';
 import 'utils.dart';
 
 /// Tests whether or not the git command-line app is available for use.
 Future<bool> get isInstalled {
   if (_isGitInstalledCache != null) {
     // TODO(rnystrom): The sleep is to pump the message queue. Can use
     // Future.immediate() when #3356 is fixed.
     return sleep(0).transform((_) => _isGitInstalledCache);
   }
 
   return _gitCommand.transform((git) => git != null);
 }
 
 /// Run a git process with [args] from [workingDir]. Returns the stdout as a
 /// list of strings if it succeeded. Completes to an exception if it failed.
-Future<List<String>> run(List<String> args, [String workingDir]) {
+Future<List<String>> run(List<String> args, {String workingDir}) {
   return _gitCommand.chain((git) {
     return runProcess(git, args, workingDir: workingDir);
   }).transform((result) {
     if (!result.success) throw new Exception(
         'Git error. Command: git ${Strings.join(args, " ")}\n'
         '${Strings.join(result.stderr, "\n")}');
 
     return result.stdout;
   });
 }
@@ skipping 39 matching lines @@
   });
 
   future.handleException((err) {
     // If the process failed, they probably don't have it.
     completer.complete(false);
     return true;
   });
 
   return completer.future;
 }