Switch perf.dart completely over to Fasta parser.
Switch perf.dart completely over to Fasta parser.

The only remaining code in perf.dart that was using the legacy
analyzer parser was in parseDirectives, which is part of setup, and
not part of the code being performance tested, so there should be no
effect on the benchmark.

Change-Id: I4676b10c367d477499c96f5220e622bb390752a4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/100680
Reviewed-by: Samuel Rawlins <5cf2cac5eec2ad6d0eb2b0f4ff6af9a590ce2bf6@google.com>
Commit-Queue: Paul Berry <72d414e3a99fb120308437779d51667bcc0984eb@google.com>

dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk