Normative: Guard IntegerIndexedElementSet with receiver check (#1556)

Author: shvaikalesh

spec.html

@@ -14648,8 +14648,10 @@ <h1>
           1. If Type(_P_) is String, then
             1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
             1. If _numericIndex_ is not *undefined*, then
-              1. Perform ? IntegerIndexedElementSet(_O_, _numericIndex_, _V_).
-              1. Return *true*.
+              1. If SameValue(_O_, _Receiver_) is *true*, then
+                1. Perform ? IntegerIndexedElementSet(_O_, _numericIndex_, _V_).
+                1. Return *true*.
+              1. If IsValidIntegerIndex(_O_, _numericIndex_) is *false*, return *true*.
           1. Return ? OrdinarySet(_O_, _P_, _V_, _Receiver_).
         </emu-alg>
       </emu-clause>