Fix 61093: mail crashes on startup.

mailnews/base/resources/content/mailWindowOverlay.xul

@@ -25,8 +25,8 @@ Rights Reserved.
 <!DOCTYPE window [
 <!ENTITY % messengerDTD SYSTEM "chrome://messenger/locale/messenger.dtd" >
 %messengerDTD;
-<!ENTITY % navigatorDTD SYSTEM "chrome://navigator/locale/navigator.dtd" >
+<!ENTITY % contentAreaCommandsDTD SYSTEM "chrome://communicator/locale/contentAreaCommands.dtd" >
-%navigatorDTD;
+%contentAreaCommandsDTD;
 ]>  
 <overlay
   xmlns:nc="http://home.netscape.com/NC-rdf#"