ava: super slowdown with power assert / jsx / stateless component

Description

If you add a test that looks like this (add it 4 or 5x to get the full impact):

It will run fast

import test  from 'ava';
import { render } from 'react-dom'
import React from 'react';
function CustomComponent({ value }) { return <input value={value} /> }
test('does something fast', t => {
    const div = document.createElement('div')
    render(<CustomComponent value="3" />, div)
    const originInput = div.getElementsByTagName('input')[0]
    const val = originInput.value
    t.same(val, 33) // assert on a reference to the value
})

But if you do this it will be very slow

function CustomComponent({ value }) { return <input value={value} /> }
test('does something slow', t => {
    const div = document.createElement('div')
    render(<CustomComponent value="3" />, div)
    const originInput = div.getElementsByTagName('input')[0]
    t.same(originInput.value, 33) // assert directly on the value
})

Changing it to use assert will also make it run very fast, so this is probably a power-assert issue, but I don’t know that as well.

In the little test case, it may add up to 1s to the full test output (timed with DEBUG=ava), but in my real life app it added 10s after the first test 20s after the second, etc until my tests just hung.

Possibly related to https://github.com/power-assert-js/power-assert/issues/34

Environment

Node.js v4.3.2
darwin 14.5.0

ava@latest and 0.9.2