fix some minor wizard bugs

mailnews/base/prefs/resources/content/aw-done.js

@@ -41,7 +41,7 @@ function setDivTextFromForm(divid, value) {
     // hide the .label if the div has no value
     if (!value || value =="") {
         var div = document.getElementById(divid + ".label");
-        div.style.display="none";
+        div.setAttribute("hidden","true");
         return;
     }
 

mailnews/base/prefs/resources/content/aw-identity.js

@@ -102,14 +102,7 @@ function checkForDomain()
   currentDomain = accountData.domain;
   
   var postEmailText = document.getElementById("postEmailText");
-  if (postEmailText) {
-    if (postEmailText.firstChild)
-      postEmailText.removeChild(postEmailText.firstChild);
-
-    var domainText = "@" + currentDomain;
-    postEmailText.appendChild(document.createTextNode(domainText));
-  }
-
+  postEmailText.setAttribute("value", "@" + currentDomain);
 }
 
 function checkForFullName() {