Deal with the BOM in the signature.
--- a/webvtt/webvtt.html Tue Nov 12 10:51:39 2013 +0800
+++ b/webvtt/webvtt.html Wed Nov 13 11:41:35 2013 +0800
@@ -2028,6 +2028,9 @@
<em>not</em> U+000A LINE FEED (LF) characters. Let <var
title="">line</var> be those characters, if any.</p></li>
+ <li><p>If the first character is a U+FEFF BYTE ORDER MARK (BOM)
+ character, remove it from <var title="">line</var>.</p></li>
+
<li><p>If <var title="">line</var> is less than six characters
long, then abort these steps. The file does not start with the
correct <a>WebVTT file</a> signature and was therefore not