Require symbol description

[feross]

I propose enabling the symbol-description rule.

Example of incorrect code:

var foo = Symbol()

Examples of correct code:

var foo = Symbol('some description')

var someString = 'some description'
var bar = Symbol(someString)

http://eslint.org/docs/rules/symbol-description

[feross]

No ecosystem impact:

# tests 422
# pass  422

[feross]

This will be part of standard v9.