Revert the recent rev of package:markdown
Revert the recent rev of package:markdown

Bug: b/236358256
Change-Id: I0efb4965ba01addc41cc3b71f23ae1276fc653b9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/248941
Commit-Queue: Devon Carew <e996497f4f2225f0ee7a9f4d1696ee710b488b66@google.com>
Reviewed-by: Ivan Inozemtsev <485d797b24cb233840f738205d28b40bd33bdaad@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk