interop broken #501

In utils we use:

const kDestroyed = Symbol('kDestroyed')
const kIsErrored = Symbol('kIsErrored')
const kIsReadable = Symbol('kIsReadable')
const kIsDisturbed = Symbol('kIsDisturbed')

But that means that using helper methods with node core stream will give incorrect results. I believe we need to also check the methods from 'stream'.

Alternatively change the core implementation to not use symbols...