This is a testharness.js-based test.
Found 8 FAIL, 0 TIMEOUT, 0 NOTRUN.
[FAIL] DeviceChangeEvent interface: existence and properties of interface object
  assert_own_property: self does not have own property "DeviceChangeEvent" expected property "DeviceChangeEvent" missing
[FAIL] DeviceChangeEvent interface object length
  assert_own_property: self does not have own property "DeviceChangeEvent" expected property "DeviceChangeEvent" missing
[FAIL] DeviceChangeEvent interface object name
  assert_own_property: self does not have own property "DeviceChangeEvent" expected property "DeviceChangeEvent" missing
[FAIL] DeviceChangeEvent interface: existence and properties of interface prototype object
  assert_own_property: self does not have own property "DeviceChangeEvent" expected property "DeviceChangeEvent" missing
[FAIL] DeviceChangeEvent interface: existence and properties of interface prototype object's "constructor" property
  assert_own_property: self does not have own property "DeviceChangeEvent" expected property "DeviceChangeEvent" missing
[FAIL] DeviceChangeEvent interface: existence and properties of interface prototype object's @@unscopables property
  assert_own_property: self does not have own property "DeviceChangeEvent" expected property "DeviceChangeEvent" missing
[FAIL] DeviceChangeEvent interface: attribute devices
  assert_own_property: self does not have own property "DeviceChangeEvent" expected property "DeviceChangeEvent" missing
[FAIL] DeviceChangeEvent interface: attribute userInsertedDevices
  assert_own_property: self does not have own property "DeviceChangeEvent" expected property "DeviceChangeEvent" missing
Harness: the test ran to completion.