Intermittent failure in /XMLHttpRequest/responsexml-document-properties.htm, /html/dom/documents/resource-metadata-management/document-lastModified-01.html

[jdm]

  ▶ Unexpected subtest result in /XMLHttpRequest/responsexml-document-properties.htm:
  │ FAIL [expected PASS] lastModified set to time of response if no HTTP header provided
  │   → assert_less_than_equal: expected a number less than or equal to 1478411709 but got 1478415309
  │ 
  │ @http://web-platform.test:8000/XMLHttpRequest/responsexml-document-properties.htm:39:9
  │ Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:1401:20
  │ test@http://web-platform.test:8000/resources/testharness.js:501:9
  └ @http://web-platform.test:8000/XMLHttpRequest/responsexml-document-properties.htm:35:7

  ▶ Unexpected subtest result in /html/dom/documents/resource-metadata-management/document-lastModified-01.html:
  │ FAIL [expected PASS] Date returned by lastModified is current at page load
  │   → assert_approx_equals: expected 1478411913 +/- 2.5 but got 1478415513
  │ 
  │ @http://web-platform.test:8000/html/dom/documents/resource-metadata-management/document-lastModified-01.html:8:5
  │ Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:1401:20
  │ test@http://web-platform.test:8000/resources/testharness.js:501:9
  └ @http://web-platform.test:8000/html/dom/documents/resource-metadata-management/document-lastModified-01.html:7:3

  ▶ Unexpected subtest result in /html/dom/documents/resource-metadata-management/document-lastModified-01.html:
  │ FAIL [expected PASS] Date returned by lastModified is current after timeout.
  │   → assert_approx_equals: (initial value was 1478415513) expected 1478411917 +/- 2.5 but got 1478415517
  │ 
  │ @http://web-platform.test:8000/html/dom/documents/resource-metadata-management/document-lastModified-01.html:41:7
  │ Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:1401:20
  └ @http://web-platform.test:8000/html/dom/documents/resource-metadata-management/document-lastModified-01.html:38:5