Vector:
mw.util.addPortlet('p-twinkle', 'TW', '#p-cactions');
mw.util.addPortletLink('p-twinkle','#', 'Hello world');
Additional changes:
* Add aria labels to gadget created menus
Additional changes to template
* Remove self closing tag on input[checkbox] in template
* Rearrange vector-menu and vector-menu-dropdown classes
for consistency between two approaches
Bug: T342815
Change-Id: I938928c3625099ad49bec8aafb11f91190a9f494
