* jsdoc ?Type adds optionality to parameters
Chrome devtools expects that parameters with type `?T` (or `T?`) add
null to `T` and optionality to the parameter. Previously it only added
null to the type.
Currently the PR does *not* add undefined to the type of
`T`, which is expected by chrome-devtools-frontend, but is inconsistent
with typescript's rules. The implementation achieves this inconsistency by
exploiting the fact that checking the signature adds optionality and
checking the parameter adds `undefined`.
* Update chrome-devtools-frontend baseline
* Add optionality only for jsdoc postfix=
* Skip jsdoc prefix types in isJSDocOptionalParameter
Previously isJSDocOptionalParameter was incorrect for types like
`?number=`, which are optional but have JSDocNullableType as their root
type node.
