Expose _overrideDeviceScaleFactor property on iOS (currently macOS only)
Pull request: https://github.com/WebKit/WebKit/pull/3984
<rdar://problem/99518927>
Committed 254126@main (bf2449abf730): <https://commits.webkit.org/254126@main> Reviewed commits have been landed. Closing PR #3984 and removing active labels.