Keep a dictionary of user email address to person object

(imported from commit 16d63fefff3bda33cfc2f90398539b5e2d9bb499)

tools/jslint/check-all.js

@@ -60,7 +60,7 @@ var globals =
     // zephyr.js
     + ' message_array message_dict get_updates_params'
     + ' clear_table add_to_table add_messages'
-    + ' subject_dict same_stream_and_subject'
+    + ' subject_dict people_dict same_stream_and_subject'
     + ' keep_pointer_in_view move_pointer_at_page_top_and_bottom'
     + ' respond_to_message'
     + ' select_message select_message_by_id'

zephyr/static/js/zephyr.js

@@ -2,6 +2,7 @@ var message_array = [];
 var message_dict = {};
 var message_in_table = {zhome: {}, zfilt: {}};
 var subject_dict = {};
+var people_dict = {};
 
 var viewport = $(window);
 
@@ -28,6 +29,17 @@ var message_groups = {
 
 var disable_pointer_movement = false;
 
+function add_person(person) {
+    people_list.push(person);
+    people_dict[person.email] = person;
+}
+
+$(function () {
+    $.each(people_list, function (idx, person) {
+        people_dict[person.email] = person;
+    });
+});
+
 // Why do we look at the 'bottom' in above_view_threshold and the top
 // in below_view_threshold as opposed to vice versa?  Mostly to handle
 // the case of gigantic messages.  Imagine the case of a selected
@@ -452,7 +464,7 @@ function add_message_metadata(message, dummy) {
         // Do the hasOwnProperty() call via the prototype to avoid problems
         // with keys like "hasOwnProperty"
         if (! typeahead_helper.known_to_typeahead(person)) {
-            people_list.push(person);
+            add_person(person);
             typeahead_helper.autocomplete_needs_update(true);
         }
     });