[masonry-slack-valid.html]
  [e.style['masonry-slack'\] = "normal" should set the property value]
    expected: FAIL

  [e.style['masonry-slack'\] = "0" should set the property value]
    expected: FAIL

  [e.style['masonry-slack'\] = "1px" should set the property value]
    expected: FAIL

  [e.style['masonry-slack'\] = "calc(2em + 3ex)" should set the property value]
    expected: FAIL

  [e.style['masonry-slack'\] = "4%" should set the property value]
    expected: FAIL

  [e.style['masonry-slack'\] = "5vmin" should set the property value]
    expected: FAIL