Navigation Menu Button Example: fix unreachable code and shift-tab no…

…t closing menu (pull #716)

* fixed unreachable code problem described in issue #396.
* Made shift-tab close menu as described in issue #588.

examples/menu-button/js/MenuItemLinks.js

@@ -76,15 +76,17 @@ MenuItemLinks.prototype.handleKeydown = function (event) {
   if (event.shiftKey) {
     if (isPrintableCharacter(char)) {
       this.menu.setFocusByFirstCharacter(this, char);
+      flag = true;
+    }
+
+    if (event.keyCode === this.keyCode.TAB) {
+      this.menu.setFocusToController();
+      this.menu.close(true);
     }
   }
   else {
     switch (event.keyCode) {
 
-      case this.keyCode.SPACE:
-        flag = true;
-        break;
-
       case this.keyCode.ESC:
         this.menu.setFocusToController();
         this.menu.close(true);

examples/menu-button/js/PopupMenuLinks.js

@@ -48,7 +48,7 @@ var PopupMenuLinks = function (domNode, controllerObj) {
   var childElement = domNode.firstElementChild;
   while (childElement) {
     var menuitem = childElement.firstElementChild;
-    if (menuitem && menuitem === 'A') {
+    if (menuitem && menuitem.tagName !== 'A') {
       throw new Error(msgPrefix + 'has descendant elements that are not A elements.');
     }
     childElement = childElement.nextElementSibling;