Bug 1235154 - Port Bug 869086 to fix right click urlbar error [TypeError this.parentNode.firstChild.focus is not a function] r=Ratty

References:
Bug 869086 - Make textbox.xml resilient against the changes in bug 653881
Bug 653881 - Fix up our XBL1 shadow tree implementation so that we can reuse it for XBL2

suite/browser/urlbarBindings.xml

@@ -661,8 +661,10 @@
       <children/>
       <xul:menupopup anonid="input-box-contextmenu"
                      class="textbox-contextmenu"
-                     onpopupshowing="if (document.commandDispatcher.focusedElement != this.parentNode.firstChild)
-                                       this.parentNode.firstChild.focus();
+                     onpopupshowing="var input =
+                                       this.parentNode.getElementsByAttribute('anonid', 'input')[0];
+                                     if (document.commandDispatcher.focusedElement != input)
+                                       input.focus();
                                      this.parentNode._doPopupItemEnabling(this);"
                      oncommand="var cmd = event.originalTarget.getAttribute('cmd'); if(cmd) { this.parentNode.doCommand(cmd); event.stopPropagation(); }">
         <xul:menuitem label="&undoCmd.label;" accesskey="&undoCmd.accesskey;" cmd="cmd_undo"/>