Investigate utilities to simplify a11y for WebComponents

[rodneyrehm]

With Custom Elements on the rise and the specification itself promoting the use of WAI-ARIA it is even more important to make this stuff as simple as possible.

The <taco-button> example illustrates how disabling a role="button" is supposed to work: by removing tabindex, onclick, onkeypress and adding aria-disabled="true" - that is a lot of DOM action necessary to compensate for something otherwise as simple as <button … disabled>.

It looks like form element semantics like [disabled] and :disabled will be available to Type Extensions (<input … is="my-cool-thing">) only.