fix tests

Author: khiga8

test/relative-time.js

@@ -1892,7 +1892,7 @@ suite('relative-time', function () {
  time.setAttribute('aria-hidden', 'false')
  await Promise.resolve()
 
- assert.isNull(time.querySelector('[aria-hidden]'), 'Expected no aria-hidden to be present')
+ assert.isNull(time.shadowRoot.querySelector('[aria-hidden]'), 'Expected no aria-hidden to be present')
  assert.isNull(time.shadowRoot.querySelector('span'), 'Expected no span to be present')
  })