After this pull request merged:
https://github.com/servo/servo/pull/7209
the 'script' component would never enter a 'built' state. In other
words, if one calls `mach build`, lets it complete, then calls `mach
build` again, the 'script' component would rebuild even though we
supposedly just built it. This was due to the `ParserResults.pkl`
getting placed in the `components/script` directory instead of the
output directory, causing cargo to think that there were unbuilt files.
Source-Repo: https://github.com/servo/servo
Source-Revision: ded6159d48901fc814d4b4395102fdbe0d9e5817
c8b19b1713