As requested in #31691 the incremental compiler should be able to
initialize its state from a previously generated dill file.
This CL introduces that functionally.
It is tested, but actual usage (e.g. proper invalidation of old files)
should live outside of the front-end (i.e. it's the callers responsibility).
One option would be for the caller to load the dill file and use the
included sources to invalidate changed files.
On my machine a from-scratch compile of dart2js takes ~5 seconds,
one initialized from such an output and with a single file invalidated
(though it actually hasn't changed) it takes ~1 second and the resulting
dill file is bit-perfect compared to the from-scratch compiled one.
Closes#31691.
Change-Id: I07f5efca5f2684d73f6c252f2dbc2ad04e9b5cd0
Reviewed-on: https://dart-review.googlesource.com/37260
Commit-Queue: Jens Johansen <jensj@google.com>
Reviewed-by: Kevin Millikin <kmillikin@google.com>
Jens Johansen
c3b992dcd8