This is a testharness.js-based test.
Found 18 FAIL, 0 TIMEOUT, 0 NOTRUN.
[FAIL] MutationEvent interface: existence and properties of interface object
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface object length
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface object name
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: existence and properties of interface prototype object
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: existence and properties of interface prototype object's "constructor" property
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: existence and properties of interface prototype object's @@unscopables property
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: constant MODIFICATION on interface object
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: constant MODIFICATION on interface prototype object
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: constant ADDITION on interface object
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: constant ADDITION on interface prototype object
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: constant REMOVAL on interface object
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: constant REMOVAL on interface prototype object
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: attribute relatedNode
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: attribute prevValue
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: attribute newValue
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: attribute attrName
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: attribute attrChange
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
[FAIL] MutationEvent interface: operation initMutationEvent(DOMString, optional boolean, optional boolean, optional Node?, optional DOMString, optional DOMString, optional DOMString, optional unsigned short)
  assert_own_property: self does not have own property "MutationEvent" expected property "MutationEvent" missing
Harness: the test ran to completion.