Unprefix -moz-{min|max}-content CSS keyword #1992

Sites are relying on the CSS keyword max-content that we have in a vendor-prefixed state.
We should investigate if there are differences between our implementation and the spec, but at the very least for a quick fix we should provide an alias (alias the prefixed version to a renamed unprefixed implementation)

Sites are relying on the CSS keyword `max-content` that we have in a vendor-prefixed state. We should investigate if there are differences between our implementation and the spec, but at the very least for a quick fix we should provide an alias (alias the prefixed version to a renamed unprefixed implementation)

I did some investigation into this using the MDN max-content page for testing, comparing between the latest Basilisk and the latest Chromium.

I discovered that we don't have max-content prefixed for all CSS properties, it is only prefixed for certain CSS properties.

In the first example on the page max-content is applied to the weight property. It appears we do have max-content prefixed for the weight and height CSS properties.

On the second example on the page max-content is applied to the grid-template-columns property. This test correctly renders as we do not have max-content prefixed for the grid-template-columns property.

In Bugzilla bug 1322780 they unprefixed both max-content and min-content at the same time.

I did some investigation into this using the [MDN max-content page](https://developer.mozilla.org/en-US/docs/Web/CSS/max-content) for testing, comparing between the latest Basilisk and the latest Chromium. I discovered that we don't have `max-content` prefixed for all CSS properties, it is only prefixed for certain CSS properties. In the first example on the page `max-content` is applied to the `weight` property. It appears we do have `max-content` prefixed for the `weight` and `height` CSS properties. On the second example on the page `max-content` is applied to the `grid-template-columns` property. This test correctly renders as we do not have `max-content` prefixed for the `grid-template-columns` property. In Bugzilla bug [1322780](https://bugzilla.mozilla.org/show_bug.cgi?id=1322780) they unprefixed both `max-content` and `min-content` at the same time.

Since this has been used un-prefixed for a while we can keep this simple and just change the use cases where the prefixed version is still used and not bother with aliasing it, since it's extremely unlikely sites would have only prefixed versions of the CSS keyword in use (as that would not be compatible with current mainstream browser versions).

I should be able to push this out on short notice to include in 31.3.0.

Of note, while extremely unlikely it'll be in use, it would be prudent to check application front-end code to see if -moz-min-content or -moz-max-content is actually in use for e.g. theming.

Since this has been used un-prefixed for a while we can keep this simple and just change the use cases where the prefixed version is still used and not bother with aliasing it, since it's _extremely_ unlikely sites would have only prefixed versions of the CSS keyword in use (as that would not be compatible with current mainstream browser versions). I should be able to push this out on short notice to include in 31.3.0. Of note, while extremely unlikely it'll be in use, it would be prudent to check application front-end code to see if -moz-min-content or -moz-max-content is actually in use for e.g. theming.

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Unprefix -moz-{min|max}-content CSS keyword #1992