fix api bustage from bug #206252 for thunderbird

mail/components/compose/content/MsgComposeCommands.js

@@ -2249,7 +2249,7 @@ function AddAttachment(attachment)
     var item = document.createElement("listitem");
 
     if (!attachment.name)
-      attachment.name = gMsgCompose.AttachmentPrettyName(attachment.url);
+      attachment.name = gMsgCompose.AttachmentPrettyName(attachment.url, attachment.urlCharset);
 
     // for security reasons, don't allow *-message:// uris to leak out
     // we don't want to reveal the .slt path (for mailbox://), or the username or hostname