[css-display-3] Can the root float?

[fantasai]

In #8095 we established that:

• the root establishes an independent formatting context
• the ICB establishes a block formatting context (thus an in-flow root is a block-level box)

This fully defines the root box’s layout.

However, we noted that some implementations don't handle float on the root element, so we have a question: should float apply to the root element? If not, is that a used value of none or do we compute it to none?

Current testing shows that Blink and Webkit can float the root, and Gecko can't. Also, among the print implementations some support float, some don't, and some don't have proper block layout on the root

[bfgeek]

My (strong) preference here is that the ICB layout context should contain minimal "special" logic. E.g. if somebody wants to float the root - let it float!

[astearns]

@emilio would Gecko have any concerns with specifying that the root can float?

[emilio]

Not in principle, though I don't have the context for that limitation. Maybe @dbaron does?

[Loirooriol]

Servo and Ladybird allow it to float.