This is a testharness.js-based test.
[FAIL] e.style['width'] = "var(--x ())" should set the property value
  assert_not_equals: property should be set got disallowed value ""
[FAIL] e.style['width'] = "var(--x () )" should set the property value
  assert_not_equals: property should be set got disallowed value ""
[FAIL] e.style['width'] = "var(--x() )" should set the property value
  assert_not_equals: property should be set got disallowed value ""
[FAIL] e.style['width'] = "var(--x (),)" should set the property value
  assert_not_equals: property should be set got disallowed value ""
[FAIL] e.style['width'] = "var(--x(),)" should set the property value
  assert_not_equals: property should be set got disallowed value ""
[FAIL] e.style['width'] = "var({--x})" should set the property value
  assert_not_equals: property should be set got disallowed value ""
[FAIL] e.style['width'] = "var({--x}, 10px)" should set the property value
  assert_not_equals: property should be set got disallowed value ""
[FAIL] e.style['width'] = "var({--x, --y})" should set the property value
  assert_not_equals: property should be set got disallowed value ""
Harness: the test ran to completion.