11.9.5 Strict does-not-equal operator

EqualityExpression : EqualityExpression !== RelationalExpression
EqualityExpressionNoIn : EqualityExpressionNoIn !== RelationalExpressionNoIn

function evaluate(EqualityExpression !== RelationalExpression) {
var lref = evaluate(EqualityExpression);
var lval = GetValue(lref);
var rref = evaluate(RelationalExpression);
var rval = GetValue(rref);
var r = StrictEqualityComparison(lval, rval); // 11.9.6
if (r) return false;
return true;
}