Move gn _run target generation into test().

gin/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_overrides/v8.gni")
 import("//testing/test.gni")
 
 component("gin") {
   sources = [
     "arguments.cc",
@@ skipping 184 matching lines @@
     "test/expect.js",
     "test/file_unittests.js",
     "test/gtest_unittests.js",
     "../OWNERS",
   ]
 
   data_deps = [
     ":gin_shell",
   ]
 }
-
-# TODO(GYP): Delete this after we've converted everything to GN.
-# The _run targets exist only for compatibility w/ GYP.
-group("gin_unittests_run") {
-  testonly = true
-  deps = [
-    ":gin_unittests",
-  ]
-}