Get rid of unneeded Future.immediate() calls.

utils/pub/pub.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.
 
 /// The main entrypoint for the pub command line application.
 library pub;
 
 import 'dart:async';
 import '../../pkg/args/lib/args.dart';
 import '../../pkg/path/lib/path.dart' as path;
@@ skipping 228 matching lines @@
       // TODO(rnystrom): Will eventually need better logic to walk up
       // subdirectories until we hit one that looks package-like. For now, just
       // assume the cwd is it.
       future = Entrypoint.load(path.current, cache);
     }
 
     future = future.then((entrypoint) {
       this.entrypoint = entrypoint;
       try {
         var commandFuture = onRun();
-        if (commandFuture == null) return new Future.immediate(true);
+        if (commandFuture == null) return true;
 
         return commandFuture;
       } catch (error, trace) {
         handleError(error, trace);
-        return new Future.immediate(null);
       }
     });
 
-
     future
       .then((_) => cache_.deleteTempDir())
       .catchError((asyncError) {
         var e = asyncError.error;
         if (e is PubspecNotFoundException && e.name == null) {
           e = 'Could not find a file named "pubspec.yaml" in the directory '
             '${path.current}.';
         } else if (e is PubspecHasNoNameException && e.name == null) {
           e = 'pubspec.yaml is missing the required "name" field (e.g. "name: '
             '${basename(path.current)}").';
@@ skipping 33 matching lines @@
     if (exception is HttpException || exception is HttpParserException ||
         exception is SocketIOException || exception is PubHttpException) {
       return exit_codes.UNAVAILABLE;
     } else if (exception is FormatException) {
       return exit_codes.DATA;
     } else {
       return 1;
     }
   }
 }