Implement the full suite of W3C global attributes

From https://html.spec.whatwg.org/multipage/dom.html#global-attributes:

- [x] [accesskey](https://html.spec.whatwg.org/multipage/interaction.html#the-accesskey-attribute)
- [x] [autocapitalize](https://html.spec.whatwg.org/multipage/interaction.html#attr-autocapitalize)
- [x] [autofocus](https://html.spec.whatwg.org/multipage/interaction.html#attr-fe-autofocus)
- [x] class
- [x] [contenteditable](https://html.spec.whatwg.org/multipage/interaction.html#attr-contenteditable)
- [x] [data-*](https://html.spec.whatwg.org/multipage/dom.html#embedding-custom-non-visible-data-with-the-data-*-attributes) https://github.com/jverkoey/slipstream/issues/134
- [x] [dir](https://html.spec.whatwg.org/multipage/dom.html#attr-dir)
- [x] [draggable](https://html.spec.whatwg.org/multipage/dnd.html#attr-draggable)
- [x] [enterkeyhint](https://html.spec.whatwg.org/multipage/interaction.html#attr-enterkeyhint)
- [x] [hidden](https://html.spec.whatwg.org/multipage/interaction.html#attr-hidden)
- [x] id
- [x] [inert](https://html.spec.whatwg.org/multipage/interaction.html#the-inert-attribute)
- [x] [inputmode](https://html.spec.whatwg.org/multipage/interaction.html#attr-inputmode)
- [ ] [is](https://html.spec.whatwg.org/multipage/custom-elements.html#attr-is)
- [x] [itemid](https://html.spec.whatwg.org/multipage/microdata.html#attr-itemid)
- [x] [itemprop](https://html.spec.whatwg.org/multipage/microdata.html#names:-the-itemprop-attribute)
- [x] [itemref](https://html.spec.whatwg.org/multipage/microdata.html#attr-itemref)
- [x] [itemscope](https://html.spec.whatwg.org/multipage/microdata.html#attr-itemscope)
- [x] [itemtype](https://html.spec.whatwg.org/multipage/microdata.html#attr-itemtype)
- [x] [lang](https://html.spec.whatwg.org/multipage/dom.html#attr-lang)
- [x] [nonce](https://html.spec.whatwg.org/multipage/urls-and-fetching.html#attr-nonce)
- [x] [popover](https://html.spec.whatwg.org/multipage/popover.html#attr-popover)
- [x] slot
- [x] [spellcheck](https://html.spec.whatwg.org/multipage/interaction.html#attr-spellcheck)
- [x] [style](https://html.spec.whatwg.org/multipage/dom.html#attr-style)
- [x] [tabindex](https://html.spec.whatwg.org/multipage/interaction.html#attr-tabindex)
- [ ] [title](https://html.spec.whatwg.org/multipage/dom.html#attr-title)
- [x] [translate](https://html.spec.whatwg.org/multipage/dom.html#attr-translate)
- [x] [writingsuggestions](https://html.spec.whatwg.org/multipage/interaction.html#attr-writingsuggestions)