Add a --no-precompile flag.

lib/src/command/upgrade.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.
 
 import 'dart:async';
 
 import '../command.dart';
 import '../log.dart' as log;
 import '../solver/version_solver.dart';
 
 /// Handles the `upgrade` pub command.
 class UpgradeCommand extends PubCommand {
   String get name => "upgrade";
   String get description =>
       "Upgrade the current package's dependencies to latest versions.";
   String get invocation => "pub upgrade [dependencies...]";
   String get docUrl => "http://dartlang.org/tools/pub/cmd/pub-upgrade.html";
   List<String> get aliases => const ["update"];
 
   bool get isOffline => argResults['offline'];
 
   UpgradeCommand() {
     argParser.addFlag('offline',
         help: 'Use cached packages instead of accessing the network.');
 
     argParser.addFlag('dry-run', abbr: 'n', negatable: false,
         help: "Report what dependencies would change but don't change any.");
+
+    argParser.addFlag('precompile', defaultsTo: true,
+        help: "Precompile executables and transformed dependencies.");
   }
 
   Future run() async {
-    var dryRun = argResults['dry-run'];
     await entrypoint.acquireDependencies(SolveType.UPGRADE,
-        useLatest: argResults.rest, dryRun: dryRun);
+        useLatest: argResults.rest,
+        dryRun: argResults['dry-run'],
+        precompile: argResults['precompile']);
+
     if (isOffline) {
       log.warning("Warning: Upgrading when offline may not update you to the "
                   "latest versions of your dependencies.");
     }
   }
 }