[API Review] RT-20906: Support setting min/pref/max sizes via css

[Richard Bair]

Sounds good.

BTW I have a duplicate issue RT-21564, which is also duplicate of RT-27785. I'll close RT-21564 as duplicate of 27785 and 20906.

> Percentage values are not allowed since the actual value would need to be computed from the width and/or height of the Node's parent before the parent is laid out.

What happens if somebody uses a percentage?