This change adds experimental option '--import-dill' to front-end server
to specify existing kernel file to import when compiling a new one.
Newly generated kernel file will depend on the imported one and will
omit libraries available in the imported dill file, as well as platform
libraries.
Caveat: the new option is not compatible with '--incremental'.
Change-Id: Id637908afdb12f1829e5f634251fa9ad82676baf
Reviewed-on: https://dart-review.googlesource.com/54309
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Alexander Markov
3ca5d165af