Avoid neested CDATA section for PPR e.g. with Primefaces

In PPR with Primefaces a neested CDATA section is rendered for components with script sections. I attached a patch for the HtmlResponseWriterImpl in myfaces-shared which avoid the double rendering of the CDATA section.
Primefaces uses startCDATA and endCDATA of ResponseWriter for it's cdata section. I've overridden this two methods to memorise if a cdata section is open.

If a cdata section is open it's not opened a second one. I added this check to the writeScriptContent() method because there occurse the problem with Primefaces.

Please review the patch because I'm not sure if there are any site effects.

Thanks,

Regards Marcus