Use native css custom properties when available

[sorvell]

Currently, even when native css custom properties are available, Polymer still shims css custom properties. We cannot simply turn off the shimming in this case because Polymer uses an unimplemented but proposed native feature @apply.

We'll need to shim @apply as css custom properties to be able to use native css custom properties.

[mgiuffrida]

Great, glad to see this is high priority! 👍

[abdonrd]

👍

[klebba]

👍

[Jamtis]

👍

[ebidel]

Any word on this @sorvell? I think some of this has landed?

[ebidel]

This landed as an opt-in features in 1.6.0!

https://www.polymer-project.org/1.0/docs/release-notes#v-1-6-0

[mgiuffrida]

It does have several issues, so buyer beware: #3802 #3803 #3800 #3801 #3806 (some fixed in master)

[ebidel]

Reopening for @sorvell to close when he things this is ready for mass exposure.

[abdonrd]

@ebidel ready? :)

[ebidel]

Seems like all the open issues are closed.

[mgiuffrida]

we switched it on in Chrome WebUI and nothing has caught fire yet

[abdonrd]

Nice! 🎉