Add null check for drawingArea in RemoteScrollingCoordinatorProxy::layerTreeHost()
rdar://85499764
Pull request: https://github.com/WebKit/WebKit/pull/1963
Committed 252028@main (b712db6f6c95): <https://commits.webkit.org/252028@main> Reviewed commits have been landed. Closing PR #1963 and removing active labels.
*** Bug 243226 has been marked as a duplicate of this bug. ***