Extract all data that Program::global_declaration_instantiation()
needs from the AST into value-type metadata stored on the Script
object, computed once during construction. This includes lexical
names, var names, functions to initialize, var scoped names, AnnexB
candidates, and lexical bindings.
This prepares for rewriting GDI to use the pre-computed metadata
instead of walking the AST.
This moves the responsibility of setting up a SourceCode object to the
users of JS::Lexer.
This means Lexer and Parser are free to use string views into the
SourceCode internally while working.
It also means Lexer no longer has to think about anything other than
UTF-16 (or ASCII) inputs. So the unit test for parsing various invalid
UTF-8 sequences is deleted here.
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.
