Add two endpoint params to `comment` endpoint

This was requested by Chrome for being able to warn about content in
draft comments.

Release-Notes: skip
Google-Bug-Id: b/253320131
Change-Id: I1a649d1a306c7b2b68a6a3e43a0383a24418427f

polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts

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 af7c64f..4a05739 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
+++ b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
@@ -513,6 +513,13 @@
         </gr-endpoint-param>
         <gr-endpoint-param name="editing" .value=${this.editing}>
         </gr-endpoint-param>
+        <gr-endpoint-param name="message" .value=${this.messageText}>
+        </gr-endpoint-param>
+        <gr-endpoint-param
+          name="isDraft"
+          .value=${isDraftOrUnsaved(this.comment)}
+        >
+        </gr-endpoint-param>
         <div id="container" class=${classMap(classes)}>
           ${this.renderHeader()}
           <div class="body">