WebKit: JSC: Incorrect LoadVarargs handling in ArgumentsEliminationPhase::transform(CVE-2017-7056)

Here is a snippet of ArgumentsEliminationPhase::transform case LoadVarargs: ... if candidate-op == PhantomNewArrayWithSpread || candidate-op == PhantomSpread ... if argumentCountIncludingThis limit storeArgumentCountIncludingThisargumentCountIncludingThis; // store arguments ... node-remove;...