Use ICU case conversion/transliterator for case conversion behind a flag

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("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
 if (is_android) {
@@ skipping 383 matching lines @@
     "src/js/harmony-species.js",
     "src/js/harmony-unicode-regexps.js",
     "src/js/harmony-string-padding.js",
     "src/js/promise-extra.js",
   ]
 
   outputs = [
     "$target_gen_dir/experimental-libraries.cc",
   ]
 
+  if (v8_enable_i18n_support) {
+    sources += [ "src/js/icu-case-mapping.js" ]
+  }
+
   args = [
            rebase_path("$target_gen_dir/experimental-libraries.cc",
                        root_build_dir),
            "EXPERIMENTAL",
          ] + rebase_path(sources, root_build_dir)
 
   if (v8_use_external_startup_data) {
     outputs += [ "$target_gen_dir/libraries_experimental.bin" ]
     args += [
       "--startup_blob",
@@ skipping 1889 matching lines @@
     ":v8",
     ":v8_libplatform",
     "//build/config/sanitizers:deps",
     "//build/win:default_exe_manifest",
   ]
 
   if (v8_enable_i18n_support) {
     deps += [ "//third_party/icu" ]
   }
 }