Merge branch 'update-variable-name' into 'master'

Update -font-size variable name

See merge request gitlab-org/gitlab-ce!23519

app/assets/stylesheets/framework/highlight.scss

@@ -47,7 +47,7 @@
     a {
       font-family: $monospace-font;
       display: block;
-      font-size: $code_font_size !important;
+      font-size: $code-font-size !important;
       min-height: 19px;
       white-space: nowrap;