Support unprefixed min-content and max-content and treat the prefixed
version as aliases for
1. width, min-width, max-width if inline-axis is horizontal, and
2. height, min-height, max-height if inline-axis is vertical, and
3. inline-size, min-inline-size, max-inline-size, and
4. flex-basis.

Besides, update the test cases to use unprefixed max-content and
min-content.

Differential Revision: https://phabricator.services.mozilla.com/D7536