* Add caret color
* Add missing descriptions
* Update browser support

…the Ed draft value 'auto' is implemented over the WD 'instant'.

Add/update descriptions. Remove values no longer in spec.

…and add the symbols() from that spec to list-style(-type)

…mostly more concise descriptions

…move spec to new location. Fix incorrect order of syntax examples

…Haven't added descriptions for the WebKit ones yet, as there are so many of them and neither Chrome or Safari have a great reference site.

Update ::content and mark that it is renamed to ::slotted in latest draft

Add:

* ::region
* ::shadow
* ::slotted


Updated ::first-letter, ::first-line, and ::selection. The former two are split out into this spec in Selectors L4 and the latter was removed from Selectors L3. Fixed browser support info and updated descriptions.

Added:

* ::spelling-error
* ::grammar-error
* ::placeholder

Spec hasn't been updated in 13 years and the pseudo elements have either been removed or moved to Pseudo Elements L4 in the latest Editors draft.

Removed:
* ::after(2)
* ::before(2)
* ::alternate
* ::line-marker
* ::outside
* ::outside(2)

Updated:

* ::before
* ::after
* ::marker

…and remove the moz ones that should be pseudo elements.

…to match the latest state of both specs.

…add descriptions, change to correct spec level, update browser support, add missing entries.

Current, current(), past, future. Add descriptions, update spec links, fix browser support for current/current()

…and mark as non-standard.

…They’re already listed in the pseudo element section and the double colon syntax is well supported now.

…by removing "The [feature name] pseudo class" type text from start of each

…and generate the new browser.js file for this and previous changed.

New:

* @custom-media
* @font-feature-values
* @scope (replaces old @host somewhat)

…and tidy up @-moz-document’s descriiption

* @host (dropped from Shadow DOM. Now @scope and friends exist in the CSS Scoping spec)
* @string and @counter. Not implemented and from a very old  Working Draft from last decade. Latest ED doesn't contain these, and they were never defined in the old spec.

Fixes #1655