There is a missing FontCascade include in FontCascadeDescription.cpp.
Pull request: https://github.com/WebKit/WebKit/pull/6840
Committed 257049@main (5da705d3b3dc): <https://commits.webkit.org/257049@main> Reviewed commits have been landed. Closing PR #6840 and removing active labels.
<rdar://problem/102694537>