Merge branch 'diff-stats-perf-bar' into 'master'

Fixes diff stats not being visible with performance bar

See merge request gitlab-org/gitlab-ce!22390

app/assets/stylesheets/pages/diff.scss

@@ -1013,6 +1013,7 @@
 
   .with-performance-bar & {
     top: 135px;
+    max-height: calc(100vh - 135px);
   }
 }
 

changelogs/unreleased/diff-stats-perf-bar.yml

+---
+title: Fixed diff stats not showing when performance bar is enabled
+merge_request:
+author:
+type: fixed