Credit to @ayumihamsaki. Fixes#4400.
- Added WAI-ARIA to the layout templates files.
- Added Focus-ring polyfill to allow better keyboard navigation and screen reader support.
- Added WAI-ARIA to tabs and created keyboard arrow controls for tabs.
- Added event.key polyfill to allow removal of deprecated event.keyCode, event.charCode and event.which.
- Fixed all the whitespace, tabbing and indent issues with all the lang files.
- Keyboard navigation now allows the following key actions: Tab, Up Arrow, Down Arrow, Left Arrow, Right Arrow, Home and End buttons.
- Added keyboard navigation for tab panels.
22847e7892