The previous support for @name tags suppressing inference from
surrounding code was ad-hoc and incomplete. This commit makes a @name
tag (or a tag acting as a @kind/@name shorthand combo, like @function)
detach the `ast` field from the comment context, so that the surrounding
code will be universally ignored per the JSDoc spec.

Per usejsdoc.org, this tag goes either in a comment attached to a
function that has declared that function to be a class, or in a comment
on an ES6 class constructor.