* Replaced assertJump, assertRevert and expectThrow with shouldFail.
* Fixed linter errors.
* Fixed typo.
* Made the helpers async.
(cherry picked from commit b0da0fded0)
* separate part of ERC721Mintable into ERC721MetadataMintable
* remove mint and burn from 721 tests
* Fixed linter error.
* fix ERC721 mint tests
* Minor fixes.
(cherry picked from commit 744f567f40)