Remove support for the special "assets" directory.

sdk/lib/_internal/pub/test/serve/serve_from_dependency_asset_test.dart

Index: sdk/lib/_internal/pub/test/serve/serve_from_dependency_asset_test.dart
diff --git a/sdk/lib/_internal/pub/test/serve/serve_from_dependency_asset_test.dart b/sdk/lib/_internal/pub/test/serve/serve_from_dependency_asset_test.dart
deleted file mode 100644
index f026d8aacd9c94d456c15edf4c93524dfc6c2707..0000000000000000000000000000000000000000
--- a/sdk/lib/_internal/pub/test/serve/serve_from_dependency_asset_test.dart
+++ /dev/null
@@ -1,39 +0,0 @@
-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.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';
-import 'utils.dart';
-
-main() {
-  initConfig();
-  integration("'assets' URLs look in the dependency's asset directory", () {
-    d.dir("foo", [
-      d.libPubspec("foo", "0.0.1"),
-      d.dir("asset", [
-        d.file("foo.txt", "foo"),
-        d.dir("sub", [
-          d.file("bar.txt", "bar"),
-        ])
-      ])
-    ]).create();
-
-    d.dir(appPath, [
-      d.appPubspec({
-        "foo": {"path": "../foo"}
-      })
-    ]).create();
-
-    pubServe(shouldGetFirst: true);
-    requestShouldSucceed("assets/foo/foo.txt", "foo");
-    requestShouldSucceed("assets/foo/sub/bar.txt", "bar");
-
-    // "assets" cannot be in a subpath of the URL:
-    requestShould404("foo/assets/foo/foo.txt");
-    requestShould404("a/b/assets/foo/sub/bar.txt");
-    endPubServe();
-  });
-}