Core htmx AJAX headers

• should handle basic JSON HX-Trigger response header properly10ms ‣

  this.server.respondWith('GET', '/test', [200, { 'HX-Trigger': '{"foo":null}' }, ''])
  var div = make('<div hx-get="/test"></div>')
  var invokedEvent = false
  div.addEventListener('foo', function(evt) {
    invokedEvent = true
    should.equal(null, evt.detail.value)
    evt.detail.elt.should.equal(div)
  })
  div.click()
  this.server.respond()
  invokedEvent.should.equal(true)