CSS filters work similarly to canvas filters, so it makes sense to have
Gfx::Filter that can be used by both libraries in an analogous way
as Gfx::Color.
ApplyOpacity internally calls canvas.saveLayer() which requires a
matching canvas.restore() to be called.
Fixes missing header on https://supabase.com/
ApplyFilter internally calls canvas.saveLayer() which requires a
matching canvas.restore() to be called.
Fixes painting on https://supabase.com/ regressed by
8562b0e33b
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.
