Mojo C++ bindings: switch ios/web mojom targets to use STL types.

ios/web/test/BUILD.gn

 # Copyright 2016 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")
 import("//tools/grit/grit_rule.gni")
 import("//tools/grit/repack.gni")
 
 mojom("mojo_bindings") {
   sources = [
     "mojo_test.mojom",
   ]
-
-  use_new_wrapper_types = false
 }
 
 repack("packed_resources") {
   testonly = true
   sources = [
     "$root_gen_dir/ios/web/ios_web_resources.pak",
     "$root_gen_dir/ios/web/test/test_resources.pak",
   ]
   deps = [
     ":resources",
@@ skipping 14 matching lines @@
   ]
   outputs = [
     "grit/test_resources.h",
     "test_resources.pak",
   ]
   grit_flags = [
     "-E",
     "root_gen_dir=" + rebase_path(root_gen_dir, root_build_dir),
   ]
 }