Cache TTypes. This change saves us ~70KiB per compiler with just ~3KiB of cache. BUG=492725 Change-Id: I7b8053c032c9c68f646162baf61abf6db3afe52e Reviewed-on: https://chromium-review.googlesource.com/284003 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>