Support directories other than "web" in pub build.

sdk/lib/_internal/pub/test/build/includes_assets_from_dependencies_test.dart

 // Copyright (c) 2013, 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:scheduled_test/scheduled_test.dart';
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
@@ skipping 11 matching lines @@
         d.dir("sub", [
           d.file("bar.txt", "bar"),
         ])
       ])
     ]).create();
 
     d.dir(appPath, [
       d.appPubspec({
         "foo": {"path": "../foo"}
       }),
+      d.dir("example", [
+        d.file("index.html", "html"),
+      ]),
       d.dir("web", [
         d.file("index.html", "html"),
       ])
     ]).create();
 
-    schedulePub(args: ["build"],
-        output: new RegExp(r"Built 3 files!"),
-        exitCode: 0);
+    schedulePub(args: ["build", "--all"],
+        output: new RegExp(r"Built 6 files!"));
 
     d.dir(appPath, [
       d.dir('build', [
-        d.file("index.html", "html"),
-        d.dir('assets', [
-          d.dir('foo', [
-            d.file('foo.txt', 'foo'),
-            d.dir('sub', [
-              d.file('bar.txt', 'bar'),
-            ]),
+        d.dir('example', [
+          d.file("index.html", "html"),
+          d.dir('assets', [
+            d.dir('foo', [
+              d.file('foo.txt', 'foo'),
+              d.dir('sub', [
+                d.file('bar.txt', 'bar'),
+              ]),
+            ])
+          ])
+        ]),
+        d.dir('web', [
+          d.file("index.html", "html"),
+          d.dir('assets', [
+            d.dir('foo', [
+              d.file('foo.txt', 'foo'),
+              d.dir('sub', [
+                d.file('bar.txt', 'bar'),
+              ]),
+            ])
           ])
         ])
       ])
     ]).validate();
   });
 }