Merge branch 'fix-context-header-wrapping-collapse' into 'master'

Re-add width for sidebar context header

See merge request gitlab-org/gitlab-ce!16180

app/assets/stylesheets/framework/contextual-sidebar.scss

@@ -23,6 +23,7 @@
 .context-header {
   position: relative;
   margin-right: 2px;
+  width: $contextual-sidebar-width;
 
   a {
     transition: padding $sidebar-transition-duration;