7e20b1c2b1
This is in preparation for using it for parsing .options files in tests. Change-Id: I1ee750ab48de53c4af03d3ce5082a76328851e47 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/208581 Reviewed-by: Dmitry Stefantsov <dmitryas@google.com>