This is a testharness.js-based test.
Found 2 FAIL, 0 TIMEOUT, 0 NOTRUN.
[FAIL] ReadableStream interface: operation from(any)
  assert_own_property: interface object missing static operation expected property "from" missing
[FAIL] ReadableStream interface: calling from(any) on new ReadableStream() with too few arguments must throw TypeError
  assert_own_property: interface object must have static operation as own property expected property "from" missing
Harness: the test ran to completion.