Speed up Interpreter.prototype.getProperty
Speed up Interpreter.prototype.getProperty

getProperty is used a lot, and did some expensive checks
for stringness and arrayness on every lookup when only
needed for 'length' and numeric indices.

Gives a few percent boost on execution speed when looping
around property accesses.

arcatdmz/JS-Interpreter,arcatdmz/JS-Interpreter,NeilFraser/JS-Interpreter,NeilFraser/JS-Interpreter,arcatdmz/JS-Interpreter,NeilFraser/JS-Interpreter