gr-related-changes-list: Use change-model for change param

Release-Notes: skip
Change-Id: I6cd3ea252ba0bc435c2d4c132379571e0f6ee812
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
index 242bda0..eba1d18 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
@@ -1436,7 +1436,6 @@
           <div class="relatedChanges">
             <gr-related-changes-list
               id="relatedChanges"
-              .change=${this.change}
               .mergeable=${this.mergeable}
             ></gr-related-changes-list>
           </div>
diff --git a/polygerrit-ui/app/elements/change/gr-related-changes-list/gr-related-changes-list.ts b/polygerrit-ui/app/elements/change/gr-related-changes-list/gr-related-changes-list.ts
index 4aae939..a1adfb8 100644
--- a/polygerrit-ui/app/elements/change/gr-related-changes-list/gr-related-changes-list.ts
+++ b/polygerrit-ui/app/elements/change/gr-related-changes-list/gr-related-changes-list.ts
@@ -54,13 +54,13 @@
 
 @customElement('gr-related-changes-list')
 export class GrRelatedChangesList extends LitElement {
-  @property({type: Object})
-  change?: ParsedChangeInfo;
-
   @property({type: Boolean})
   mergeable?: boolean;
 
   @state()
+  change?: ParsedChangeInfo;
+
+  @state()
   latestPatchNum?: PatchSetNumber;
 
   @state()
@@ -89,6 +89,11 @@
     super();
     subscribe(
       this,
+      () => this.getChangeModel().change$,
+      x => (this.change = x)
+    );
+    subscribe(
+      this,
       () => this.getChangeModel().latestPatchNum$,
       x => (this.latestPatchNum = x)
     );