This is just odd and surprising. Per CSSOM, for all supported properties, all the different property name to attribute name conversions should always exist. Found via https://github.com/web-platform-tests/wpt/pull/26086.
-apple-color-filter should not be exposed by default.
I should've posted the whole list of properties in this category here: -apple-color-filter -apple-pay-button-style -apple-pay-button-type -apple-trailing-word I suspect the answer is we want none of these to be exposed?
The "-apple-pay" ones are different (the "-apple" isn't really a vendor prefix and they should have been called "-webkit-apple-pay-" or "-apple-apple-pay" :| About -apple-trailing-word, CSSProperties.json has this to say: "Needed for feature-detecting the Safari browser"
Fixed as part of Bug 217623.
reopened along with Bug 217623.
and fixed again