This CL uses Martins suggested fix (adding 1 to avoid shifting a
negative), and adds a simple test that compiles the parser to dart2js
(with asserts enabled) and runs it via d8. This will perhaps catch
breakage up front another time.
To my knowledge this is not a supported use case though, so likely
we can't but in much effort for any future big breakages.
Fixes https://github.com/dart-lang/sdk/issues/50048
Change-Id: Ic5ac6e63f2d6d32e38ba562ed21dbe85328935cc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/261301
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Jens Johansen <jensj@google.com>
Ryan Macnak