Bug 175346 changed event listeners for touchstart and touchmove on the document (+ body + window + document element) to be passive unless otherwise specified. This bug is going to collect any breakage from that change.
When Chrome made this change they saw a small number of sites break. Usually this appears as double scrolling, or some element moving at a different rate from the rest of the page.
Please note the URL here, and do not revert the original change. We plan to deal with this through evangelism if we can't detect in code.
Note that our guidance to affected sites is to rely on CSS touch-action instead of depending on TouchEvent.preventDefault: https://developers.google.com/web/updates/2017/01/scrolling-intervention
Really passive touch listeners are only a reasonable choice when touch-action is fully supported - see https://bugs.webkit.org/show_bug.cgi?id=133112#c2.
Safari is likely to see more web compat problems than Chrome unless/until WebKit gets touch-action support.
We haven't seen reports of this.
> Safari is likely to see more web compat problems than Chrome unless/until WebKit gets touch-action support.