Block NECP in the WebContent process sandbox if content filtering is being done in the Network process.
<rdar://problem/101688342>
Pull request: https://github.com/WebKit/WebKit/pull/6912
Committed 257139@main (747f39e11530): <https://commits.webkit.org/257139@main> Reviewed commits have been landed. Closing PR #6912 and removing active labels.