Parsing unicode regexes can cause strange behavior in Node 4

[not-an-aardvark]

Tell us about your environment

• ESLint Version: master
• Node Version: 4.7.3
• npm Version: 2.15.11

What parser (default, Babel-ESLint, etc.) are you using?

default

Please show your full configuration:

parserOptions:
  ecmaVersion: 6
rules:
  eqeqeq: [error, always, {'null': never}]

What did you do? Please include the actual source code causing the issue.

foo === /abc/u;

What did you expect to happen?

No errors

What actually happened? Please include the actual, raw output from ESLint.

1:5  error  Expected '==' and instead saw '==='  eqeqeq

---

This is happening because the node.value property of the regex literal node is null in Node 4, because unicode regular expressions don't exist in that version. As a result, the rule assumes that the node is a null literal.

The rule can be updated to check the regex property of the literal to make sure it's not a regular expression. However, I wonder if there is a better way to represent this at the parser level -- it seems unintuitive that node.type === 'Literal' && node.value === null should match against anything other than a null literal.