Native functions now only get the Interpreter& as an argument. They can
then extract |this| along with any indexed arguments it wants from it.
This forces functions that want |this| to actually deal with calling
interpreter.this_value().to_object(), and dealing with the possibility
of a non-object |this|.
This is still not great but let's keep massaging it forward.
Fix the "instanceof" operator to check if the constructor's prototype
property occurs anywhere in the prototype chain of the instance object.
This patch also adds Object.setPrototypeOf() to make it possible to
create a test for this bug.
Thanks to DexesTTP for pointing this out! :^)
This operator walks the prototype chain of the RHS value and looks for
a "prototype" property with the same value as the prototype of the LHS.
This is pretty cool. :^)
