Merge branch 'dmishunov-perf-feature-flag' into 'master'

Introducing :webperf_experiment feature flag

See merge request gitlab-org/gitlab!32083

lib/gitlab/gon_helper.rb

@@ -46,6 +46,7 @@ module Gitlab
       push_frontend_feature_flag(:monaco_blobs, default_enabled: false)
       push_frontend_feature_flag(:monaco_ci, default_enabled: false)
       push_frontend_feature_flag(:snippets_edit_vue, default_enabled: false)
+      push_frontend_feature_flag(:webperf_experiment, default_enabled: false)
     end
 
     # Exposes the state of a feature flag to the frontend code.