Remove 8px margin top for GrComment in editing mode

Screenshot: https://imgur.com/a/LM7sAC6
Google-bug-id: b/244676327
Release-Notes: skip
Change-Id: I08a43e4fb05f31da2309a4437c37ee74010a4746
diff --git a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
index 343bf51..6c58b3e 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
+++ b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
@@ -410,7 +410,7 @@
         }
         .editMessage {
           display: block;
-          margin: var(--spacing-m) 0;
+          margin-bottom: var(--spacing-m);
           width: 100%;
         }
         .show-hide {