postprocess-framework-headers-definitions is no longer needed for internal builds.
<rdar://problem/104354248>
Pull request: https://github.com/WebKit/WebKit/pull/8747
Pull request: https://github.com/WebKit/WebKit/pull/10295
Committed 260542@main (a0da8012d30d): <https://commits.webkit.org/260542@main> Reviewed commits have been landed. Closing PR #10295 and removing active labels.