CSS mask-composite is not being vendored prefixed

[alan-agius4]

The mask-composite CSS property is not being vendored prefixed.

Repro: https://esbuild.github.io/try/#dAAwLjE5LjUAewogIGxvYWRlcjogJ2NzcycsCiAgdGFyZ2V0OiBbJ2Nocm9tZTEyMiddCn0AKiB7Cm1hc2staW1hZ2U6IHJldmVydDsKbWFzay1jb21wb3NpdGU6IGV4Y2x1ZGU7Cn0

https://caniuse.com/?search=mask-composite

Esbuild version: 0.19.5

[evanw]

The mapping that you're supposed to do for this seems to be a little more complex than just a vendor prefix. From some initial research it looks like the following additional rewrites might be needed:

• mask-composite: add => -webkit-mask-composite: source-over
• mask-composite: subtract => -webkit-mask-composite: source-out
• mask-composite: intersect => -webkit-mask-composite: source-in
• mask-composite: exclude => -webkit-mask-composite: xor

I'm not familiar with this CSS property though.

[alan-agius4]

Yes, you are absolutely right, it’s far more examples than just adding a prefix.