The following test has been crashing a lot lately: CCCCCCCCCCCCCCCNCCCCCCCCCCCPCCCCCCCCCCCCCPCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCPPPCPCPPPPPPPPPPPPPPPCPPNNXPCPPPCCPPCPPCPPCPPCPPCPPPPPCCCPPCPCCPC https://build.webkit.org/results/GTK%20Linux%2064-bit%20Debug%20(Tests)/r244584%20(4645)/http/tests/security/sandboxed-iframe-ALLOWED-modals-crash-log.txt
Marking as flaky.
Fixed by r292907. Test expectations updated in https://trac.webkit.org/changeset/294140/webkit.