Clean up the deprecated (and never really official) HTML namespace by replacing with the official XHTML namespace. b=7834,42280 r=vidur

xpfe/global/resources/content/unix/printdialog.xul

@@ -26,7 +26,7 @@ Contributor(s): Masaki Katakai <katakai@japan.sun.com>
 <?xul-overlay href="chrome://global/content/dialogOverlay.xul"?>
 <!DOCTYPE window SYSTEM "chrome://global/locale/printdialog.dtd">
 
-<window xmlns:html="http://www.w3.org/TR/REC-html40"
+<window xmlns:html="http://www.w3.org/1999/xhtml"
   xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
   id="printDialog"
   onload="onLoad();"