Re: [csswg-drafts] [css-will-change] ambiguous phrasing (#4612)

I always assumed it was the 2nd, e.g. `will-change: contain` would create a stacking context because `contain: layout` does that, even if `contain: size` does not.

That's what Firefox does, but not Chromium. [Testcase](https://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A%3Cstyle%3E%0Adiv%3A%3Abefore%2C%20div%3A%3Aafter%20%7B%0A%20%20display%3A%20inline-block%3B%0A%20%20width%3A%20100%25%3B%0A%20%20vertical-align%3A%20top%3B%0A%20%20height%3A%2025px%3B%0A%7D%0Adiv%3A%3Aafter%20%7B%0A%20%20margin-top%3A%20-25px%3B%0A%7D%0A%0A%23contain-layout%3A%3Abefore%20%7B%0A%20%20content%3A%20%22PASS%20-%20%27contain%3A%20layout%27%20created%20a%20stacking%20context%22%3B%0A%20%20contain%3A%20layout%3B%0A%20%20background%3A%20lime%3B%0A%7D%0A%23contain-layout%3A%3Aafter%20%7B%0A%20%20content%3A%20%22FAIL%20-%20%27contain%3A%20layout%27%20should%20have%20created%20a%20stacking%20context%22%3B%0A%20%20background%3A%20red%3B%0A%7D%0A%0A%23contain-size%3A%3Abefore%20%7B%0A%20%20content%3A%20%22FAIL%20-%20%27contain%3A%20size%27%20shouldn%27t%20have%20created%20a%20stacking%20context%22%3B%0A%20%20contain%3A%20size%3B%0A%20%20background%3A%20red%3B%0A%7D%0A%23contain-size%3A%3Aafter%20%7B%0A%20%20content%3A%20%22PASS%20-%20%27contain%3A%20size%27%20didn%27t%20create%20a%20stacking%20context%22%3B%0A%20%20background%3A%20lime%3B%0A%7D%0A%0A%23will-change-contain%3A%3Abefore%20%7B%0A%20%20content%3A%20%22%3F%3F%20-%20%27will-change%3A%20contain%27%20DID%20create%20a%20stacking%20context%22%3B%0A%20%20will-change%3A%20contain%3B%0A%20%20background%3A%20orange%3B%0A%7D%0A%23will-change-contain%3A%3Aafter%20%7B%0A%20%20content%3A%20%22%3F%3F%20-%20%27will-change%3A%20contain%27%20did%20NOT%20create%20a%20stacking%20context%22%3B%0A%20%20background%3A%20orange%3B%0A%7D%0A%0A%23will-change-transform%3A%3Abefore%20%7B%0A%20%20content%3A%20%22PASS%20-%20%27will-change%3A%20transform%27%20created%20a%20stacking%20context%22%3B%0A%20%20will-change%3A%20transform%3B%0A%20%20background%3A%20lime%3B%0A%7D%0A%23will-).

Not sure if there are other properties like this.

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Received on Wednesday, 18 December 2019 11:19:14 UTC