[css-logical]Flow-relative syntax for transform

[TxHawks]

There is no mention of handling the values of transform in a flow-relative manner in the css-logical-1 spec, which would certainly be very helpful when authoring multi-directional styles

[nico3333fr]

Yes, there are some cases where we would really need this, I'm facing one right now for a custom toggle:

LTR:

I'm doing:

transform: translateX(<value>);

for active state.

But it will give this in RTL:

I have to do:

transform: translateX(-<value>);

To get the proper display:

Something like: translate-inline-start would replace something like:

[dir="rtl] .selector {
transform: translateX(-<value>);
}

And same for translateY, we would go for translate-block-start.

For translateZ, I guess i18n does not encounter negative 3D written stuff... so it's okay :D

[Malvoz]

Duplicate of #1544.

[dbaron]

Closing as duplicate of #1544.