Remove support of HTML plugins

Change-Id: If7b5503d57ea847e6cf2c038e589a55779fb551c
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.ts b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.ts
index b4e39f5..2868ae3 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.ts
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view_test.ts
@@ -390,7 +390,7 @@
         );
       },
       '0.1',
-      'http://some/plugins/url.html'
+      'http://some/plugins/url.js'
     );
   });
 
@@ -2861,7 +2861,7 @@
             .then(el => (hookEl = el));
         },
         '0.1',
-        'http://some/plugins/url.html'
+        'http://some/plugins/url.js'
       );
       flush(() => {
         assert.strictEqual((hookEl as any).plugin, plugin);