Fix tracebacks opening stream on streams page.

This was caused by a branch I was working on conflicting with the
stream_data.js split.

(imported from commit 995dcf1412114bd36404b8c7ef66eb6f1e89648a)

static/js/subs.js

@@ -701,7 +701,7 @@ $(function () {
         var list = sub_row.find('.subscriber_list_container ul');
         var indicator_elem = sub_row.find('.subscriber_list_loading_indicator');
 
-        if (!exports.get(stream).render_subscribers) {
+        if (!stream_data.get_sub(stream).render_subscribers) {
             return;
         }