Most computed border-radii contain their initial values, and since the
normalized initial border radii are always zero, there is no need to do
expensive floating point math to normalize them.
Elements with transforms were tested on their pre-transformed
positions, causing incorrect hits.
Copy the position transformation done in `StackingContext::hit_test`
to ensure that hit tests are done on the _actual_ position.
Implemented by reusing AddMask display list item that was initially
added for `background-clip` property.
Progress on flashlight effect on https://null.com/games/athena-crisis
For a while we used the wider Paintable type for stacking context,
because it was allowed to be created by InlinePaintable and
PaintableBox. Now, when InlinePaintable type is gone, we can use more
specific PaintableBox type for a stacking context.
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
Now that the heap has no knowledge about a JavaScript realm and is
purely for managing the memory of the heap, it does not make sense
to name this function to say that it is a non-realm variant.
