Implement main blink target in GN.

Source/bindings/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/bindings.gni")
 import("//third_party/WebKit/Source/build/scripts/scripts.gni")
 import("//third_party/WebKit/Source/core/core.gni")
 import("//third_party/WebKit/Source/modules/modules.gni")
 
+visibility = "//third_party/WebKit/*"
+
 # Main interface IDL files (excluding dependencies and testing)
 # are included as properties on global objects, and in aggregate bindings.
 main_interface_idl_files = core_idl_files + modules_idl_files
 
 main_interface_idl_files_list = "$target_gen_dir/main_interface_idl_files.tmp"
 write_file(main_interface_idl_files_list,
            rebase_path(main_interface_idl_files, root_build_dir))
 
 generated_global_constructors_idl_files = [
   "$blink_output_dir/WindowConstructors.idl",
@@ skipping 74 matching lines @@
   deps = [ ":global_objects" ]
 }
 
 # GYP version: generated.gyp:generated_idls
 group("generated_idls") {
   deps = [
     ":global_constructors_idls",
     "//third_party/WebKit/Source/core:generated_testing_idls",
   ]
 }