Don't allow page to be scaled on mobile.

CHANGELOG

@@ -71,6 +71,7 @@ v 7.8.0
   - Added support for firing system hooks on group create/destroy and adding/removing users to group (Boyan Tabakov)
   - Added persistent collapse button for left side nav bar (Jason Blanchard)
   - Prevent losing unsaved comments by automatically restoring them when comment page is loaded again.
+  - Don't allow page to be scaled on mobile.
 
 v 7.7.2
   - Update GitLab Shell to version 2.4.2 that fixes a bug when developers can push to protected branch

app/views/layouts/_head.html.haml

@@ -18,7 +18,7 @@
   = javascript_include_tag "application"
   = csrf_meta_tags
   = include_gon
-  %meta{name: 'viewport', content: 'width=device-width, initial-scale=1.0'}
+  %meta{name: 'viewport', content: 'width=device-width, initial-scale=1, maximum-scale=1'}
   %meta{name: 'theme-color', content: '#474D57'}
 
   = render 'layouts/google_analytics' if extra_config.has_key?('google_analytics_id')