Originally, 7200b3a16c introduced a two-pass system to determine
hypothetical cross sizes. Later, this was partially reverted in
0084d992d4, but some code was left behind that caused resolution of
percentages in `{min/max}-{width/height}` size constraints not to work.
Through intrinsic sizing, we can potentially end up with a definite
available space for the items in the last FC run. At that point we
should be able to resolve percentages against the available space, but
we were never doing that.
...instead of taking the Layout::Box. This will allow us to make more
nuanced decisions in those functions by having access to flex layout
internal state.
There's a specific (and thankfully very common!) scenario where we can
actually skip calculating the automatic minimum size for flex items.
In single-line (no wrapping) flex containers, if the sum of all item
flex base sizes is <= the flex container's main size, we know that
none of the items will be shrunk by the layout algorithm.
And so for any flex item with definite main size AND automatic minimum
main size, we can treat the automatic minimum size as 0.
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
If available space is definite it should always match the size of the
containing block. Therefore, there is no need to do containing block
node lookup.
