[css-position-3] Incorrect value definitions for `inset-*` shorthands

[yarusome]

The value of inset-block and inset-inline is defined as <top>{1,2}, and that of inset is <top>{1,4}.

These should be <'top'>{1,2} and <'top'>{1,4} instead.

[fantasai]

Fixed by @cdoublev in 743af48 nine months ago, marking this closed. :) Thanks for the report!