Server implementation of this class.

The server doesn't necessarily know the user agent of the client, so we combine the results of all other implementations.

class ImplServer extends SafeStylesUtilsImpl {

 ImplIE6To8 _implIE = new ImplIE6To8();

 SafeStyles forOpacity(double value) {
   SafeStylesBuilder sb = new SafeStylesBuilder();
   sb.append(super.forOpacity(value));
   sb.append(_implIE.forOpacity(value));
   return sb.toSafeStyles();
 }
}