MDL-55700 theme_noname: Allow text nodes in breadcrumb

The new theme was showing all nodes in the breadcrumb as links even when there is no
valid link.

Part of MDL-55071

lib/navigationlib.php

@@ -592,6 +592,15 @@ class navigation_node implements renderable {
         }
     }
 
+    /**
+     * Used to easily determine if this link in the breadcrumbs has a valid action/url.
+     *
+     * @return boolean
+     */
+    public function has_action() {
+        return !empty($this->action);
+    }
+
     /**
      * Gets the CSS class to add to this node to describe its type
      *

theme/noname/templates/core/navbar.mustache

@@ -1,10 +1,10 @@
 <ol class="breadcrumb" role="navigation">
     {{#get_items}}
-        {{#action}}
+        {{#has_action}}
         <li class="breadcrumb-item {{#is_active}}active{{/is_active}}"><a href="{{action}}" {{#get_title}}title="{{get_title}}"{{/get_title}}>{{text}}</a></li>
-        {{/action}}
-        {{^action}}
+        {{/has_action}}
+        {{^has_action}}
         <li class="breadcrumb-item {{#is_active}}active{{/is_active}}">{{text}}</li>
-        {{/action}}
+        {{/has_action}}
     {{/get_items}}
-</ol>
+</ol>