Remove yet more unneeded //mojo/edk/test:test_support dependencies.

services/js/system/tests/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("//mojo/public/tools/bindings/mojom.gni")
 
 source_set("js_to_cpp_tests") {
   testonly = true
 
   deps = [
     ":js_to_cpp_bindings",
     "//gin:gin_test",
-    "//mojo/edk/test:test_support",
     "//mojo/public/cpp/bindings",
     "//mojo/public/cpp/system",
     "//mojo/public/interfaces/bindings/tests:test_interfaces",
     "//services/js/system",
   ]
 
   sources = [
     "js_to_cpp_tests.cc",
   ]
 }
 
 mojom("js_to_cpp_bindings") {
   sources = [
     "js_to_cpp.mojom",
   ]
 }