Add HTMLMenuElement Web API (#2242)
Add HTMLMenuElement Web API (#2242)

Sources:
1. HTML 5 Specifications:
   https://dev.w3.org/html5/spec-LC/interactive-elements.html#the-menu-element
   https://html.spec.whatwg.org/multipage/grouping-content.html#the-menu-element
2. Manual tests on:
  - Chromium 66
  - Firefox 59
  - Opera 60
mdn/browser-compat-data,chrisdavidmills/browser-compat-data,teoli2003/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data