Regression (r252701): imported/w3c/web-platform-tests/css/css-multicol/multicol-rule-shorthand-2.xht and multicol-rule-fraction-003.xht are failing on iOS

[Aakash Jain]

imported/w3c/web-platform-tests/css/css-multicol/multicol-rule-shorthand-2.xht and multicol-rule-fraction-003.xht are failing on iOS.

Flakiness dashboard:
https://results.webkit.org/?suite=layout-tests&suite=layout-tests&test=imported%2Fw3c%2Fweb-platform-tests%2Fcss%2Fcss-multicol%2Fmulticol-rule-shorthand-2.xht&test=imported%2Fw3c%2Fweb-platform-tests%2Fcss%2Fcss-multicol%2Fmulticol-rule-shorthand-2.xht

e.g.:
https://build.webkit.org/results/Apple%20iOS%2013%20Simulator%20Release%20WK2%20(Tests)/r252704%20(1149)/results.html
https://ews-build.webkit.org/results/iOS-13-Simulator-WK2-Tests-EWS/r384074-5459-clean-tree/results.html

[Aakash Jain]

This is failing since https://trac.webkit.org/changeset/252701/webkit

TestExpectations were updated in that commit. These tests were failing for a while. After that commit, these tests started passing on mac, but still failing on iOS (this time with updated expectation of passing).

[Simon Fraser (smfr)]

Created attachment 384198 [details]
Patch

[Simon Fraser (smfr)]

https://trac.webkit.org/changeset/252802/webkit

[Radar WebKit Bug Importer]

<rdar://problem/57440950>