Fix typing of 'reply' event

Keys of HTMLElementEventMap must be strings, otherwise the internal
compile will fail.

Change-Id: Ibf3a8ed5ae118aed5fdcafd6c8c0824957a7f78f
diff --git a/polygerrit-ui/app/types/events.ts b/polygerrit-ui/app/types/events.ts
index 2c1d8a1..81482b7 100644
--- a/polygerrit-ui/app/types/events.ts
+++ b/polygerrit-ui/app/types/events.ts
@@ -56,7 +56,8 @@
 
 declare global {
   interface HTMLElementEventMap {
-    reply: ReplyEvent;
+    /* prettier-ignore */
+    'reply': ReplyEvent;
   }
 }