UI for the HTML rich elements such as the spinner. Punnycode encoded email addresses in email fields. Numerical keyboard on number fields. The whole mess wit

UI for the HTML rich elements such as the spinner. Punnycode encoded email addresses in email fields. Numerical keyboard on number fields. The whole mess with WebRTC. Video elements codecs. History API in early mobile browsers. The various APIs for storing data locally in the browser (particularly regarding blocking and size limit). Data expiration. This one is so messed up it makes me angry. Spawning a background task. And those are just the ones that popped in my head in a few minutes.