[gardening] Read nnbdMode parameter instead of field on null options.

Fixes crash introduced by https://github.com/dart-lang/sdk/commit/72e559929f7c6db5f38a9b2ad52df67aec624dfc.

Change-Id: Ie9e3cdbcd282a840dcd028661fa93e49d207d38f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/149421
Commit-Queue: Aske Simon Christensen <askesc@google.com>
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Auto-Submit: Aske Simon Christensen <askesc@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>

https://dart.googlesource.com/sdk/+/1ad89b85a2ee82e42c3b522069208892f5e7a1e7
1 file changed
tree: 9feaf5b13a88063675827b587f445068c27d148d
  1. commits.json