[null-safety] remove more usage of mockito from the framework tests (#62936)

https://dart.googlesource.com/external/github.com/flutter/flutter/+/c2e85e67c96838449369b1a7177316ae7c574d48
1 file changed
tree: 09b13451d8db2855171bd41b0df21136262367c0
  1. commits.json