Show missing filename in load no-go areas dialog

5b52abc1 copied `<label>` and `<input>` from the `loadedittrackForm` for
consistency, but missed to add some corresponding code to `NoGoAreas.js`.

After completing the implementation, the filename for loading no-go areas is now
displayed after selecting a file just like in the "Load track as route" dialog.

Test Plan:
- Open "Load no-go areas" dialog.
- Browse and select file.
- The filename should now be shown next to "Browse".

js/plugin/NogoAreas.js

@@ -98,6 +98,8 @@ BR.NogoAreas = L.Control.extend({
 
         L.DomEvent.addListener(document, 'keydown', this._keydownListener, this);
 
+        L.DomUtil.get('nogoFile').onchange = L.bind(this.onFileChanged, this);
+
         this.editTools.on(
             'editable:drawing:end',
             function (e) {
@@ -170,6 +172,11 @@ BR.NogoAreas = L.Control.extend({
         $('#nogoError').css('display', message ? 'block' : 'none');
     },
 
+    onFileChanged: function (e) {
+        if (!e.target.files[0]) return;
+        $(e.target).next('label').text(e.target.files[0].name);
+    },
+
     uploadNogos: function () {
         var self = this;