Rationalize the top-level BUILD.gn rules a bit

shell/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/ui.gni")
 import("//mojo/public/mojo.gni")
 import("//mojo/public/mojo_application.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//mojo/tools/embed/rules.gni")
 import("//testing/test.gni")
@@ skipping 15 matching lines @@
     deps += [
       ":mojo_shell_apk",
       ":mojo_shell_tests_apk",
     ]
   }
 }
 
 group("tests") {
   testonly = true
   deps = [
+    ":apptests",
     ":mojo_shell_tests",
     ":shell_nfc_apptests",
     "//shell/application_manager:mojo_application_manager_unittests",
     "//shell/crash:crash_unittests",
   ]
 }
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
@@ skipping 560 matching lines @@
       "${root_out_dir}/libmojo_shell.so",
     ]
   } else {
     sources += [ "${root_out_dir}/mojo_shell" ]
   }
 
   outputs = [
     "${root_out_dir}/symbols/{{source_file_part}}",
   ]
 }