Merge branch '21099-ie-fork-btn' into 'master'

Fix enormous IE11 fork button

## What does this MR do?
Puts a width on btn SVGs because IE can't handle `auto`

## What are the relevant issue numbers?
Closes #21099

See merge request !5982

CHANGELOG

@@ -37,6 +37,7 @@ v 8.11.3 (unreleased)
   - Allow system info page to handle case where info is unavailable
   - Label list shows all issues (opened or closed) with that label
   - Don't show resolve conflicts link before MR status is updated
+  - Fix IE11 fork button bug !598
   - Don't prevent viewing the MR when git refs for conflicts can't be found on disk
   - Fix external issue tracker "Issues" link leading to 404s
 

app/assets/stylesheets/framework/buttons.scss

@@ -200,7 +200,7 @@
 
   svg {
     height: 15px;
-    width: auto;
+    width: 15px;
     position: relative;
     top: 2px;
   }