Outstanding syntaxes needing validators

[ben-eb]

• clip-path: <clip-source> | [ <basic-shape> || <geometry-box> ] | none
• grid-auto-columns: <track-size>
• grid-column-end: <grid-line>
• grid-template-columns: none | <track-list> | <auto-track-list> | subgrid <line-name-list>?
• mask-image: <mask-reference>#
• shape-outside: none | <shape-box> || <basic-shape> | <image>
• transition-property: none | <single-transition-property># (MDN has this as IDENT which I take to mean using isCustomIdent)