Convert GN visibility to lists.

Source/bindings/core/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("//third_party/WebKit/Source/bindings/core/core.gni")
 import("//third_party/WebKit/Source/bindings/core/idl.gni")
 import("//third_party/WebKit/Source/bindings/scripts/scripts.gni")
 
-visibility = "//third_party/WebKit/*"
+visibility = [ "//third_party/WebKit/*" ]
 
 # GYP version: Source/bindings/core/generated.gyp:interfaces_info_individual_core
 compute_interfaces_info_individual("interfaces_info_individual_core") {
   sources_static = core_static_idl_files
   sources_generated = core_generated_idl_files
   component_dir = "core"
   output_file =
     "$bindings_core_output_dir/InterfacesInfoCoreIndividual.pickle"
 }