171013 - fix and hookup toolbars as text/icons/both in modern. r=varga, sr=jag

suite/browser/navigator.xul

@@ -157,6 +157,7 @@ Contributor(s):
       </hbox>
  
       <hbox id="nav-bar-inner" flex="1">
+        <observes element="nav-bar" attribute="buttonstyle"/>
         <textbox id="urlbar" class="chromeclass-location uri-element" flex="1"
                  type="autocomplete" searchSessions="history" 
                  timeout="50" maxrows="6" alwaysopenpopup="true"