This moves the five test suites for flow analysis along with the
constants test suite.
Note that a few files have formatting errors. I'll fix those in a
follow-up CL.
Change-Id: Ie9bba74c7d91e49ac6c9d3c64a96be007b6a94c6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/123680
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Paul Berry