An alias is a bare reference and cannot carry node properties, so '&b *a'
(an anchor on an alias) and a tag on an alias are malformed. parseNode
ignored any pending anchor or tag when it reached an alias token, dropping
the property and accepting the document.
The alias case now rejects a pending anchor or tag, and moves to its own
parseAlias helper so parseNode stays within the complexity limit. A bare
alias and an anchor or tag on a real node are unaffected.
Measured against the official YAML test-suite, parse-level conformance
rises from 266/333 (79.9%) to 267/333 (80.2%) with no regression.
Mihaela M
779ebe596d