[ObjC ARC] Converts ios/chrome/browser/web:web_internal to ARC.

ios/chrome/browser/web/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("//ios/web/js_compile.gni")
 
 source_set("web") {
   configs += [ "//build/config/compiler:enable_arc" ]
   sources = [
     "dom_altering_lock.h",
@@ skipping 150 matching lines @@
 js_compile_bundle("chrome_bundle") {
   closure_entry_point = "__crWeb.chromeBundle"
   sources = [
     "resources/chrome_bundle.js",
     "resources/payment_request.js",
     "resources/print.js",
   ]
 }
 
 source_set("web_internal") {
+  configs += [ "//build/config/compiler:enable_arc" ]
   sources = [
     "auto_reload_bridge.h",
     "auto_reload_bridge.mm",
     "auto_reload_controller.h",
     "auto_reload_controller.mm",
     "blocked_popup_tab_helper.h",
     "blocked_popup_tab_helper.mm",
     "chrome_web_client.h",
     "chrome_web_client.mm",
     "error_page_content.h",
@@ skipping 143 matching lines @@
     "early_page_script_perftest.mm",
   ]
   deps = [
     "//base",
     "//ios/chrome/test/base:perf_test_support",
     "//ios/web",
     "//ios/web:test_support",
   ]
   libs = [ "WebKit.framework" ]
 }