preventing ctrl-f hijacking if no search plugin is installed

public/src/app.js

@@ -539,7 +539,9 @@ var socket,
 
 			handleStatusChange();
 
-			handleSearch();
+			if (config.searchEnabled) {
+				handleSearch();
+			}
 
 			$('#logout-link').on('click', app.logout);
 

src/controllers/api.js

@@ -53,6 +53,7 @@ apiController.getConfig = function(req, res, next) {
 	config.requireEmailConfirmation = parseInt(meta.config.requireEmailConfirmation, 10) === 1;
 	config.topicPostSort = meta.config.topicPostSort || 'oldest_to_newest';
 	config.csrf_token = req.csrfToken();
+	config.searchEnabled = plugins.hasListeners('filter:search.query');
 
 	if (!req.user) {
 		if (res.locals.isAPI) {