correctly imports performance bar

app/views/layouts/_head.html.haml

@@ -43,7 +43,6 @@
   = webpack_bundle_tag "main"
   = webpack_bundle_tag "raven" if current_application_settings.clientside_sentry_enabled
   = webpack_bundle_tag "test" if Rails.env.test?
-  = webpack_bundle_tag 'performance_bar' if performance_bar_enabled?
 
   - if content_for?(:page_specific_javascripts)
     = yield :page_specific_javascripts

config/webpack.config.js

@@ -85,7 +85,6 @@ var config = {
     test:                 './test.js',
     two_factor_auth:      './two_factor_auth.js',
     users:                './users/index.js',
-    performance_bar:      './performance_bar.js',
     webpack_runtime:      './webpack.js',
   },