drafts: Avoid callback mechanism.

We had an anonymous callback for drafts that was
hard to read.  It's much easier to flatten the code,
give functions actual names, and stub them as needed
in the unit tests.

frontend_tests/node_tests/drafts.js

@@ -319,6 +319,8 @@ run_test('format_drafts', () => {
         return '<draft table stub>';
     };
 
-    drafts.setup_page();
+    drafts.open_modal = noop;
+    drafts.set_initial_element = noop;
+    drafts.launch();
     timerender.render_now = stub_render_now;
 });

static/js/drafts.js

@@ -200,7 +200,7 @@ function remove_old_drafts() {
 // Exporting for testing purpose
 exports.remove_old_drafts = remove_old_drafts;
 
-exports.setup_page = function (callback) {
+exports.launch = function () {
     function format_drafts(data) {
         var drafts = {};
         var data_array = [];
@@ -291,10 +291,6 @@ exports.setup_page = function (callback) {
         if ($("#drafts_table .draft-row").length > 0) {
             $('#drafts_table .no-drafts').hide();
         }
-
-        if (callback) {
-            callback();
-        }
     }
 
     function setup_event_handlers() {
@@ -321,6 +317,8 @@ exports.setup_page = function (callback) {
 
     remove_old_drafts();
     populate_and_fill();
+    exports.open_modal();
+    exports.set_initial_element();
     setup_event_handlers();
 };
 
@@ -448,8 +446,7 @@ exports.drafts_handle_events = function (e, event_key) {
     }
 };
 
-exports.launch = function () {
-    exports.setup_page(function () {
+exports.open_modal = function () {
     overlays.open_overlay({
         name: 'drafts',
         overlay: $('#draft_overlay'),
@@ -457,7 +454,9 @@ exports.launch = function () {
             hashchange.exit_overlay();
         },
     });
+};
 
+exports.set_initial_element = function () {
     var draft_list = drafts.draft_model.get();
     var draft_id_list = Object.getOwnPropertyNames(draft_list);
     if (draft_id_list.length > 0) {
@@ -467,7 +466,6 @@ exports.launch = function () {
         activate_element(focus_element);
         $(".drafts-list")[0].scrollTop = $('.drafts-list')[0].scrollHeight - $('.drafts-list').height();
     }
-    });
 };
 
 exports.initialize = function () {