Delete preference for Diffusion symbols

Summary:
We are doing a better job in 1) of D3069#3 and 2) is just dumb.
Let's see if someone notices this change.

Test Plan: /settings/panel/display/

Reviewers: nh, epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4789

src/applications/diffusion/controller/DiffusionBrowseFileController.php

@@ -251,10 +251,7 @@ final class DiffusionBrowseFileController extends DiffusionController {
 
         $lang = last(explode('.', $drequest->getPath()));
 
-        $prefs = $this->getRequest()->getUser()->loadPreferences();
-        $pref_symbols = $prefs->getPreference(
-          PhabricatorUserPreferences::PREFERENCE_DIFFUSION_SYMBOLS);
-        if (isset($langs[$lang]) && $pref_symbols != 'disabled') {
+        if (isset($langs[$lang])) {
           Javelin::initBehavior(
             'repository-crossreference',
             array(