tests: Delay loading old messages and starting get_updates until phantomjs thinks the page has loaded

This doesn't affect code when not in testing.  It shaves 7 seconds off of casper
test time on my machine.

(imported from commit 7e27fa781bcf16f36d9c8f058427ba57c41068bd)

static/js/message_store.js

@@ -493,7 +493,7 @@ exports.clear = function clear() {
     this.stored_messages = {};
 };
 
-$(function () {
+util.execute_early(function () {
     // get the initial message list
     function load_more(messages) {
 

static/js/server_events.js

@@ -336,7 +336,7 @@ setInterval(function () {
     watchdog_time = new_time;
 }, 5000);
 
-$(function () {
+util.execute_early(function () {
     $(document).on('unsuspend', function () {
         // Immediately poll for new events on unsuspend
         blueslip.log("Restarting get_events due to unsuspend");

static/js/util.js

@@ -345,6 +345,14 @@ if (typeof $ !== 'undefined') {
     };
 }
 
+exports.execute_early = function (func) {
+    if (page_params.test_suite) {
+        $(document).one('phantom_page_loaded', func);
+    } else {
+        $(func);
+    }
+};
+
 return exports;
 }());
 if (typeof module !== 'undefined') {

zerver/tests/frontend/common.js

@@ -62,6 +62,13 @@ exports.initialize_casper = function (viewport) {
         }
     });
 
+    casper.on('load.finished', function () {
+        casper.evaluateOrDie(function () {
+            $(document).trigger($.Event('phantom_page_loaded'));
+            return true;
+        });
+    });
+
     casper.evaluate(function () {
         window.localStorage.clear();
     });

zerver/tests/frontend/node/server_events.js

@@ -28,13 +28,13 @@ set_global('channel', {});
 set_global('home_msg_list', {
     selected_id: function () {return 1;}
 });
+set_global('page_params', {test_suite: false});
 
 
 var server_events = require('js/server_events.js');
 
 var setup = function (results) {
     server_events.home_view_loaded();
-    set_global('page_params', {});
     global.blueslip.error = function (msg, more_info, stack) {
         results.msg = msg;
         results.more_info = more_info;