bugfix: fix error in hasClass when className is regex expression

[alvteren]

When className is regexp raises the issue in packages/enzyme/src/ShallowWrapper.js on the line 1256

 TypeError: className.indexOf is not a function

[ljharb]

(－‸ლ) whoops

• i first made the existing tests consistent across shallow and mount
• since there are already hasClass tests for both shallow and mount, i moved your new tests up to that section
• i added the same tests and fix for mount

Thanks!