find, findIndex, contains will no longer check for holes

[rwaldron]

Discussion is here: https://bugs.ecmascript.org/show_bug.cgi?id=3107

Yes, inconsistent with existing Array methods, but I think better in the long term.

[ljharb]

Wait, is contains in for ES6?

[domenic]

It's technically in ES7, but will likely ship in browsers within a month or two, because version numbers don't matter ;)

[ljharb]

k, just making sure I don't get to add it to the es6-shim :-)