Allow speical keys to be bound to keystrokes

Summary: Fixes T2711. Allows special keys (arrows, tab, return) to be bound as shortcuts. Binds left and right as shortcuts in Pholio.

Test Plan: Pressed left. Pressed right.

Reviewers: chad

Reviewed By: chad

CC: aran

Maniphest Tasks: T2711

Differential Revision: https://secure.phabricator.com/D5303

src/applications/help/controller/PhabricatorHelpKeyboardShortcutController.php

@@ -21,10 +21,21 @@ final class PhabricatorHelpKeyboardShortcutController
       'description' => 'Close any dialog, including this one.',
     );
 
+    $stroke_map = array(
+      'left' => "\xE2\x86\x90",
+      'right' => "\xE2\x86\x92",
+      'up' => "\xE2\x86\x91",
+      'down' => "\xE2\x86\x93",
+      'return' => "\xE2\x8F\x8E",
+      'tab' => "\xE2\x87\xA5",
+      'delete' => "\xE2\x8C\xAB",
+    );
+
     $rows = array();
     foreach ($keys as $shortcut) {
       $keystrokes = array();
       foreach ($shortcut['keys'] as $stroke) {
+        $stroke = idx($stroke_map, $stroke, $stroke);
         $keystrokes[] = phutil_tag('kbd', array(), $stroke);
       }
       $keystrokes = phutil_implode_html(' or ', $keystrokes);