This is a testharness.js-based test.
[FAIL] XMLHttpRequest: progress events grow response body size, unknown content-length
  assert_unreached: onprogress not called multiple times, or response body did not grow. Reached unreachable code
[FAIL] XMLHttpRequest: progress events grow response body size, known content-length
  assert_unreached: onprogress not called multiple times, or response body did not grow. Reached unreachable code
Harness: the test ran to completion.