Kill most of phutil_escape_html()

Summary:
This resolves lots of double escaping.
We changed most of `phutil_render_tag(, , $s)` to `phutil_tag(, , $s)` which means that `$s` is now auto-escaped.
Also `pht()` auto escapes if it gets `PhutilSafeHTML`.

Test Plan: None.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2432

Differential Revision: https://secure.phabricator.com/D4889

src/applications/paste/controller/PhabricatorPasteListController.php

@@ -109,7 +109,7 @@ final class PhabricatorPasteListController extends PhabricatorPasteController {
       $lang_name = $paste->getLanguage();
       if ($lang_name) {
         $lang_name = idx($lang_map, $lang_name, $lang_name);
-        $item->addIcon('none', phutil_escape_html($lang_name));
+        $item->addIcon('none', $lang_name);
       }
 
       $list->addItem($item);