I'd like to pick up and second Theresa's proposal to add an auto value to the
text-decoration-skip.

Quoting from the original post:

The initial value of text-decoration-skip' is currently objects'.
However, the default platform text decoration behavior on OS X and iOS
is equivalent to `ink'. We'd like to be able to match the system
behavior by default in WebKit.

I propose we add an auto' value to text-decoration-skip'. While its
definition would give UAs broad leeway, the spec should have a
non-normative note encouraging UAs to match platform conventions for
`auto'.

Once text-decoration-skip: auto' is defined, we should change the initial value of text-decoration-skip' to be `auto'.

A quick check in Safari shows that the value of webkit-text-decoration-skip: is now auto by default, and none disables it.