jquery migrate jQuery.isArray

[kumarmj]

Issue raised based on checklist of jquery/jquery#2961

[dmethvin]

I had to revert the commit and reopen this, I should have realized that the previous 3.x versions still have this used internally and thus throw spurious errors. This is the same problem that would manifest in #156 and #246 if they were landed now.

We can either wait until jQuery Migrate 4.0 to land all these or add a version check and only give the warnings on later jQuery 3.x versions. Even with that, it makes the refactoring of the methods in core the critical path.