web: structure: use explicit field syntax for step
web: structure: use explicit field syntax for step

pattern-matching all of those values out makes the line super long and
IMO makes it less clear where values are coming from. at one point i
wanted to pass the step to another function, so rather than extending it
to `({ ... } as step)` this felt a little more natural.

Signed-off-by: Alex Suraci <925ba519bbf1a06224928b692ef88b93aee946af@gmail.com>

concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse