This reverts commit 7d5025e814.
Reason for revert: <INSERT REASONING HERE>
Original change's description:
> Fix incorrect handling of NSM forwarders and pull all logic into CFE.
>
> The original implementation was designed around a shared misunderstanding
> of optional parameter handling in the spec. (which was also ambiguous about type parameters).
>
> The correct behavior for optional/type parameters is to fill them in with their default values/bounds.
> This behavior can be implemented without any backend support, as is done in this CL.
>
> Change-Id: Ib81f17ead2d2920e755703e244db5afc328d0315
> Reviewed-on: https://dart-review.googlesource.com/52802
> Commit-Queue: Samir Jindel <sjindel@google.com>
> Reviewed-by: Dmitry Stefantsov <dmitryas@google.com>
TBR=dmitryas@google.com,sjindel@google.com
Change-Id: Ice6cd36cc62772e013bded83e0f589fe4b5e9d53
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/53400
Reviewed-by: Samir Jindel <sjindel@google.com>
Commit-Queue: Samir Jindel <sjindel@google.com>