We were conflating elements being the active element and elements being
activated. The :active pseudo class is supposed to be based on whether
an element will have its activation behavior run upon a button being
released.
Store whether an element is being activated as a flag that is set/reset
by EventHandler.
Doing this allows label elements to visually activate their control
without doing a weird paintable hack, so the Labelable classes have
been yeeted.
Instead, compute them on demand. This affects ReplacedBox and its
subclasses.
This commit is centered around a new Box::auto_content_box_size
method. It returns a SizeWithAspectRatio representing the natural
size of a replaced element, or the size derived from attributes
for text input and textarea. These values are used when the
corresponding axis is auto or indefinite.
Although introducing this API choke-point for sizing replaced and
replaced-like elements was the main goal, it's notable that layout
becomes more robust in the face of dynamic changes due to reduced
potential for stale size values (at the cost of extra calculations
and allocations).
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
