Set.prototype.difference removes the wrong element

[Ms2ger]

In step 6:

i. Let e be resultSetData[index].
ii. Set index to index + 1.
iii. If e is not empty, then

    1. Let inOther be ToBoolean(? Call(otherRec.[[Has]], otherRec.[[Set]], « e »)).
    2. If inOther is true, then
        a. Set resultSetData[index] to empty.

substeps ii. and iii. should be swapped to avoid erasing the element after the matching one.