Don't load assets unnecessarily when precompiling executables.

sdk/lib/_internal/pub/test/hosted/offline_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.
 
 library pub_tests;
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   initConfig();
 
   forBothPubGetAndUpgrade((command) {
     integration('upgrades a package using the cache', () {
       // Run the server so that we know what URL to use in the system cache.
-      servePackages([]);
+      serveNoPackages();
 
       d.cacheDir({
         "foo": ["1.2.2", "1.2.3"],
         "bar": ["1.2.3"]
       }, includePubspecs: true).create();
 
       d.appDir({
         "foo": "any",
         "bar": "any"
       }).create();
 
       var warning = null;
       if (command == RunCommand.upgrade) {
         warning = "Warning: Upgrading when offline may not update you "
                   "to the latest versions of your dependencies.";
       }
 
       pubCommand(command, args: ['--offline'], warning: warning);
 
       d.packagesDir({
         "foo": "1.2.3",
         "bar": "1.2.3"
       }).validate();
     });
 
     integration('fails gracefully if a dependency is not cached', () {
       // Run the server so that we know what URL to use in the system cache.
-      servePackages([]);
+      serveNoPackages();
 
       d.appDir({"foo": "any"}).create();
 
       pubCommand(command, args: ['--offline'],
           error: "Could not find package foo in cache.");
     });
 
     integration('fails gracefully no cached versions match', () {
       // Run the server so that we know what URL to use in the system cache.
-      servePackages([]);
+      serveNoPackages();
 
       d.cacheDir({
         "foo": ["1.2.2", "1.2.3"]
       }, includePubspecs: true).create();
 
       d.appDir({"foo": ">2.0.0"}).create();
 
       pubCommand(command, args: ['--offline'], error:
           "Package foo has no versions that match >2.0.0 derived from:\n"
           "- myapp 0.0.0 depends on version >2.0.0");
     });
   });
 }