node fixtures: Use better data for subscription update.

The dispatch test here really only cares that values
get passed on.

Note that the dispatch code ignores the email field, because
we only send subscription/update events to the user
whose subscription has changed.

frontend_tests/node_tests/lib/events.js

@@ -552,10 +552,11 @@ exports.fixtures = {
     subscription__update: {
         type: "subscription",
         op: "update",
-        name: "devel",
-        stream_id: 43,
-        property: "color",
-        value: "black",
+        email: exports.test_user.email,
+        name: streams.devel.name,
+        stream_id: streams.devel.stream_id,
+        property: "pin_to_top",
+        value: true,
     },
 
     typing__start: {