Front-end marks certain calls (currently in collection literals) as
not requiring covariant parameter checks (invariant).
VM can use that flag to generate calls through unchecked entry point.
TEST=vm/cc/StreamingFlowGraphBuilder_InvariantFlagInListLiterals
Change-Id: I8d0dc09ea4867f41d20f6d7b6ba9e0940ff555dd
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/175880
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>