[Freestyler] Fix spinner causing flickering for summary element

Fixed: 376384398
Change-Id: Icc6312df59e5c654125da6a76e116ff9371d6f41
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/5973209
Reviewed-by: Nikolay Vitkov <[email protected]>
Auto-Submit: Ergün Erdoğmuş <[email protected]>
Commit-Queue: Ergün Erdoğmuş <[email protected]>

Author: ergunsh

front_end/ui/components/spinners/spinner.css

@@ -5,6 +5,7 @@
  */
 
 :host {
+  overflow: hidden;
   width: var(--sys-size-7);
   height: var(--sys-size-7);
   display: inline-block;