Each of the *_Fasta test cases has a lot of test cases from the
corresponding *Mixin mixin. I started to combine _all_ of these
in parser_test.dart, but the file became too long; the formatter
was freezing IntelliJ.
So I've extracted out the non-test classes into parser_test_base.dart.
I'd like to extract each test class into its own file. For now, I
reduce half a dozen *_Fasta/*Mixin pairs into individual test classes.
Change-Id: I8dd7f28a6fe23e31f956cdb2f1d221669db376dc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/176064
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>