minor polish for autocomplete prefs dialog. r=kerz sr=hewitt

xpfe/components/prefwindow/resources/content/pref-smart_browsing-ac.xul

@@ -32,6 +32,7 @@
 
 <window id="pref-smart_browsing-ac" title="&autoCompleteAdvanced.title;"
         orient="vertical"
+        class="dialog"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
 
   <script type="application/x-javascript"><![CDATA[

xpfe/components/prefwindow/resources/content/pref-smart_browsing.js

@@ -155,7 +155,7 @@ function moreInfo()
 function showACAdvanced()
 {
   window.openDialog("chrome://communicator/content/pref/pref-smart_browsing-ac.xul", "", 
-                    "modal=yes,chrome,resizable=yes",
+                    "modal=yes,chrome,dialog=yes",
                     document.getElementById("browserUrlbarAutoFill").getAttribute("value"),
                     document.getElementById("browserUrlbarShowPopup").getAttribute("value"),
                     document.getElementById("browserUrlbarShowSearch").getAttribute("value"));