    // if strings aren't used in the url, getPropertyValue will escape the string, which breaks assert.include
      unescaped = actual.replace(/\\/g, '');
      assert.include(unescaped, url);
    } else if (!window.ShadyCSS || ShadyCSS.nativeCss) {
      propertyName = '--mixin2' + window.ShadyCSS.ApplyShim._separator + 'background';
      actual = getComputedStyle(e).getPropertyValue(propertyName);
      // if strings aren't used in the url, getPropertyValue will escape the string, which breaks assert.in