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. :^)
