R1:7982b23eb405

Use `PhutilXHPASTBinary` methods

Summary: Use `PhutilXHPASTBinary` methods instead of `xhpast_parse` functions. Depends on D11517.

Test Plan: N/A, this is a direct swap.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D11612