Merge branch 'revert-0be93623' into 'master'

Revert "Merge branch 'remove-unused-css-from-mr-24724' into 'master'"

See merge request gitlab-org/gitlab-ce!26609

app/assets/stylesheets/framework/common.scss

@@ -415,6 +415,12 @@ img.emoji {
 .ws-normal { white-space: normal; }
 .overflow-auto { overflow: auto; }
 
+.d-flex-center {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
 /** COMMON SIZING CLASSES **/
 .w-0 { width: 0; }