Support text-wrap: balance in legacy line layout

[David Choi]

Given that IFC and LFC are radically different in their treatment of laying out inline content, there must exist a separate implementation of `text-wrap: balance` in both codepaths. IFC is easier to work with, and therefore allows more complex implementations of text-balancing than LFC. In LFC, if we decide to implement `text-wrap: balance`, then it will likely have to be a simple approach, such as a binary search approach that runs line layout in a loop.

[Radar WebKit Bug Importer]

<rdar://problem/113595624>

[David Choi]

Pull request: https://github.com/WebKit/WebKit/pull/16502

[zalan]

(In reply to David Choi from comment #0)
> Given that IFC and LFC are radically different in their treatment of laying
> out inline content, there must exist a separate implementation of
> `text-wrap: balance` in both codepaths. IFC is easier to work with, and
> therefore allows more complex implementations of text-balancing than LFC. In
> LFC, if we decide to implement `text-wrap: balance`, then it will likely
> have to be a simple approach, such as a binary search approach that runs
> line layout in a loop.
Just a small correction; LFC stands for Layout Formatting Context. It is an umbrella project for WebKit's next-gen layout. IFC (Inline Formatting Context) is part of this initiative and it implements CSS inline layout.
Legacy line layout is the fallback codepath for content not supported by IFC.

[zalan]

not applicable anymore.