Did not migrate null_bottom / null_is_bottom type tests. Modified
null_test to not run some mirrors related checks on platforms that don't
support mirrors.
Bug:
Change-Id: I7fce784f537cc298e2945a32073700083d9275f8
Reviewed-on: https://dart-review.googlesource.com/7848
Commit-Queue: Ben Konyi <bkonyi@google.com>
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Reviewed-by: Leaf Petersen <leafp@google.com>
Ben Konyi