Information about a single float.
Information about the floats next to a flow.
Encapsulates information about floats. This is optimized to avoid allocation if there are
no floats, and to avoid copying when translating the list of floats downward.
All the information necessary to place a float.
The speculated inline sizes of floats flowing through or around a flow (depending on whether
the flow is a block formatting context). These speculations are always upper bounds; the
actual inline sizes might be less. Note that this implies that a speculated value of zero is a
guarantee that there will be no floats on that side.