The WPTs imported/w3c/web-platform-tests/dom/events/non-cancelable-when-passive/passive-[mouse]wheel-event-listener-on-document.html were previously failing due to a lack of support of wheel events in our testdriver-vendor.js, but even after addressing said issue in bug 243272, we see that the WPTs are when run on WKTR. Note that these same WPTs do _not_ fail when run through safaridriver, and from comparing against other WPTs using the wheel actions interface, it doesn't look like the interface implemented as a resolution to bug 243272 is wrong. It seems like both wheel and mousewheel events are always marked cancelable, even when in a passive event listener.
<rdar://problem/117579703>