Don't load assets unnecessarily when precompiling executables.

sdk/lib/_internal/pub/test/global/list_test.dart

 // Copyright (c) 2014, 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 'package:path/path.dart' as p;
 
 import '../../lib/src/io.dart';
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   initConfig();
 
   integration('lists an activated hosted package', () {
-    servePackages([
-      packageMap('foo', '1.0.0')
-    ]);
+    servePackages((builder) {
+      builder.serve('foo', '1.0.0');
+    });
 
     schedulePub(args: ['global', 'activate', 'foo']);
 
     schedulePub(args: ['global', 'list'], output: 'foo 1.0.0');
   });
 
   integration('lists an activated Git package', () {
     ensureGit();
 
     d.git('foo.git', [
@@ skipping 18 matching lines @@
     ]).create();
 
     schedulePub(args: ['global', 'activate', '-spath', '../foo']);
 
     var path = canonicalize(p.join(sandboxDir, 'foo'));
     schedulePub(args: ['global', 'list'],
         output: 'foo 1.0.0 at path "$path"');
   });
 
   integration('lists activated packages in alphabetical order', () {
-    servePackages([
-      packageMap('aaa', '1.0.0'),
-      packageMap('bbb', '1.0.0'),
-      packageMap('ccc', '1.0.0')
-    ]);
+    servePackages((builder) {
+      builder.serve('aaa', '1.0.0');
+      builder.serve('bbb', '1.0.0');
+      builder.serve('ccc', '1.0.0');
+    });
 
     schedulePub(args: ['global', 'activate', 'ccc']);
     schedulePub(args: ['global', 'activate', 'aaa']);
     schedulePub(args: ['global', 'activate', 'bbb']);
 
     schedulePub(args: ['global', 'list'], output: '''
 aaa 1.0.0
 bbb 1.0.0
 ccc 1.0.0
 ''');
   });
 
   integration('lists nothing when no packages activated', () {
     schedulePub(args: ['global', 'list'], output: '\n');
   });
 }