* @return The set of supported properties.
*/
private ImmutableStylePropertySet getSupportedProperties(
PropertyDetailsSet detailsSet) {
ImmutableStylePropertySet supportedProperties =
detailsSet.getSupportedProperties();
MutableStylePropertySet propertySet =
supportedProperties.createMutableStylePropertySet();
// CSS 2.1 only supports the content property for ::before and ::after.
// CSS 3 provides additional support for most selectors but we only
// support for li::marker from that additonal set.
//