generated-parser-behavior.spec.js: Switch from first/rest to head/tail
generated-parser-behavior.spec.js: Switch from first/rest to head/tail

Follow-up to these commits:

  e510ecc3d01103b61b504128cee5341dd8c4e005
  a4a66a2e5be41832bcf23127a37515d155b700bc

Mingun/pegjs,pegjs/pegjs,Mingun/pegjs,pegjs/pegjs