If all the parameter default values end up in locals, the lexical
environment we create to hold them would never be used for anything,
and so we can elide it and avoid the GC work.
The new test case crashes during bytecode generation due to
`emit_super_reference` not correctly generating the reference record
for the property access.
Even though calling delete on a super property will ultimately throw a
ReferenceError, we must return the allocated register for the result of
the delete operation (which would normally be a boolean). If the delete
operation is used in a return statement, the bytecode generator for the
return statement must be able to assume the statement had some output.
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.
