Wrong error for `late var` in this_reference_in_late_field_test, class_member_declarations_test

[eernstg]

In the test language_2/nnbd/static_errors/this_reference_in_late_field_test.dart, case 01 has a variable declared late var x = this;. With NNBD this is not an error (cf. this grammar rule and this issue comment), but the analyzer reports the following error:

ERROR|SYNTACTIC_ERROR|CONFLICTING_MODIFIERS|/b/s/w/ir/cache/builder/sdk/out/ReleaseX64/generated_tests/language_2/nnbd/static_errors/this_reference_in_late_field_test_01.dart|14|8|3|Members can't be declared to be both 'var' and 'late'.

The same issue exists for declarations starting with late var in language_2/nnbd/syntax/class_member_declarations_test.dart.

[scheglov]

@danrubel Is this a known issue?