Added ajaxify.isCold()

And used it in app.js, so window.scrollTo(0, 0); is not called
on cold load (since you're already at the top). Useful in low-
bandwidth modes since you might accidentally get kicked to the
top of the page due to a slow connection and delayed .init().

Slightly related to testing in #6150

public/src/ajaxify.js

@@ -37,6 +37,7 @@ $(document).ready(function () {
 		}
 	});
 
+	ajaxify.count = 0;
 	ajaxify.currentPage = null;
 
 	ajaxify.go = function (url, callback, quiet) {
@@ -100,6 +101,10 @@ $(document).ready(function () {
 		return true;
 	};
 
+	ajaxify.isCold = function () {
+		return ajaxify.count <= 1;
+	};
+
 	ajaxify.handleRedirects = function (url) {
 		url = ajaxify.removeRelativePath(url.replace(/^\/|\/$/g, '')).toLowerCase();
 		var isClientToAdmin = url.startsWith('admin') && window.location.pathname.indexOf(RELATIVE_PATH + '/admin') !== 0;
@@ -113,7 +118,6 @@ $(document).ready(function () {
 		return false;
 	};
 
-
 	ajaxify.start = function (url) {
 		url = ajaxify.removeRelativePath(url.replace(/^\/|\/$/g, ''));
 
@@ -123,6 +127,8 @@ $(document).ready(function () {
 
 		$(window).trigger('action:ajaxify.start', payload);
 
+		ajaxify.count += 1;
+
 		return payload.url;
 	};
 
@@ -197,7 +203,6 @@ $(document).ready(function () {
 
 	ajaxify.end = function (url, tpl_url) {
 		var count = 2;
-
 		function done() {
 			count -= 1;
 			if (count === 0) {
@@ -205,7 +210,6 @@ $(document).ready(function () {
 			}
 		}
 		ajaxify.loadScript(tpl_url, done);
-
 		ajaxify.widgets.render(tpl_url, done);
 
 		$(window).trigger('action:ajaxify.contentLoaded', { url: url, tpl: tpl_url });

public/src/app.js

@@ -278,7 +278,9 @@ app.cacheBuster = null;
 		app.replaceSelfLinks();
 
 		// Scroll back to top of page
+		if (!ajaxify.isCold()) {
 			window.scrollTo(0, 0);
+		}
 	};
 
 	app.showMessages = function () {