No functional changes - we can still very easily get to the global
object via `Realm::global_object()`. This is in preparation of moving
the intrinsics to the realm and no longer having to pass a global
object when allocating any object.
In a few (now, and many more in subsequent commits) places we get a
realm using `GlobalObject::associated_realm()`, this is intended to be
temporary. For example, create() functions will later receive the same
treatment and are passed a realm instead of a global object.
The three major changes are:
- Parsing parameters, the function body, and then the full assembled
function source all separately. This is required by the spec, as
function parameters and body must be valid each on their own, which
cannot be guaranteed if we only ever parse the full function.
- Returning an ECMAScriptFunctionObject instead of a FunctionExpression
that needs to be evaluated separately. This vastly simplifies the
{Async,AsyncGenerator,Generator,}Function constructor implementations.
Drop '_node' from the function name accordingly.
- The prototype is now determined via GetPrototypeFromConstructor and
passed to OrdinaryFunctionCreate.
This is another major milestone on our journey towards removing global
VM exception state :^)
Does pretty much exactly what it says on the tin: updating
ASTNode::execute() to return a Completion instead of a plain value. This
will *also* allow us to eventually remove the non-standard unwinding
mechanism and purely rely on the various completion types.
