PERF: Skip compressing locales for faster rebuilds (#7501)

* Do not brotli all locales in precompile

* Try without gzip

* uglify without compressing, always gzip

* skip uglify for unused locales

* FIX: Uglifier needs harmony for ES6 compatibility

* Use node uglifier if available

* Minor refactor

config/environments/production.rb

@@ -12,7 +12,8 @@ Discourse::Application.configure do
   # Disable Rails's static asset server (Apache or nginx will already do this)
   config.public_file_server.enabled = GlobalSetting.serve_static_assets || false
 
-  config.assets.js_compressor = :uglifier
+  require 'uglifier'
+  config.assets.js_compressor = Uglifier.new(harmony: true)
 
   # stuff should be pre-compiled
   config.assets.compile = false