This adds code to ignore trailing `?` in `as` and `is` expressions
because the trailing `?` may be part of the larger expression.
At the moment, this change is a no-op, but will become active
when a subsequent CL lands support for nullable types as part of
https://github.com/dart-lang/language/issues/110
Change-Id: I829d6aee0f11957ca9b5e143000005031649449f
Reviewed-on: https://dart-review.googlesource.com/c/86960
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Dan Rubel
e2db9676d9