- Delete defined but not implemented
`ConservativeVectorBase& operator=(ConservativeVectorBase const&);`
- Mark `ConservativeVectorBase` as non-copyable because underlying
`m_list_node` cannot be copied safely.
- Change `ConservativeVector` copy assignment to simply copy elements
from one vector to another, since we don't have to worry about
`ConservativeVectorBase` while copying.
`ConservativeVector`, `RootVector` and `RootHashMap` are final types,
and their base classes have a protected destructor, so when their
destructor is called, the static and dynamic types will be the same
(can't destruct them through a pointer to a base or derived class).
Therefore, there is no need for a virtual destructor.
This fixes the newly introduced `-Wunnecessary-virtual-specifier`
Clang warning (llvm/llvm-project#131188).
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
