Replace String.split with StringUtils.splitWorker.

This performs an order of magnitude better than String.split
when using multiple delimiters (a Regular Expression when using
String.split).

Note that Domain.parseDomain is one of the worst performing parts
of Galimatias. The regex-based split was one of the reasons.
URLUtils.percentDecode: Use String.getBytes only if we have to.

String.getBytes was one of the performance issues with
URLUtils.percentDecode, and as such, with Domain.parseDomain.