Validation improvements and FIXMEs
Validation improvements and FIXMEs

- Canonicalize passed-in domain using new URL(...)
- Ensure passed-in domain matches host or hostname or is a dotted suffix of hostname
- Parse nonnumeric expires using new Date(...)
- Reserialize expires using Date's toGMTString
- Added a FIXME to add Public Suffix List validation
- Added a FIXME to switch to HTTP Set-Cookie-compatible date parsing for Expires
bsittler/async-cookies-api,bsittler/async-cookies-api