[[Fix]] Don't warn when RegExp() is used without 'new'.

[lauriro]

https://262.ecma-international.org/#sec-regexp-constructor
...
function call RegExp(…) is equivalent
to the object creation expression new RegExp(…)
with the same arguments
...

[coveralls]

Coverage remained the same at 100.0% when pulling df7d2c1 on lauriro:fix-regexp-warn into 2d4a3d1 on jshint:master.

[jugglinmike]

Thanks for the patch--this is a good idea!

It's a bit more refactoring than I'd typically like to see in a bug fix, but I'm not particularly fond of how the code is currently written, so I'll take it :)

[lauriro]

It was a bit more refactoring than I would liked to do but just extending the string triggered line length error.

.. and string.indexOf would give false-positives for Arr(), Boo(), and so on.

After pull request I found that Function is also missing.