Add a function for narrowing by time travel

(imported from commit 1f8871309a34b0bfef79b671d308d6219f4377b4)

zephyr/jstemplates/actions_popover_content.html

@@ -12,7 +12,7 @@
 
   {{#if narrowed}}
   <li>
-    <a onclick="ui.hide_actions_popover(); narrow.activate([], {then_select_id: {{message.id}} });">
+    <a onclick="ui.hide_actions_popover(); narrow.by_time_travel({{message.id}});">
       <i class="icon-time"></i> Narrow to messages around this time
     </a>
   </li>

zephyr/static/js/narrow.js

@@ -377,6 +377,10 @@ exports.by_recipient = function (target_id) {
     }
 };
 
+exports.by_time_travel = function (target_id) {
+    narrow.activate([], { then_select_id: target_id });
+};
+
 exports.deactivate = function () {
     if (!filter_function) {
         return;