[[Size]] can be a negative integer or negative inf

[Table 1](https://tc39.es/proposal-set-methods/#table-set-record-fields) defines `[[Size]]` as:
> a non-negative [integer](https://tc39.es/ecma262/#integer) or +∞

But it can actually also be a negative integer or -∞, because it's coerced through [ToIntegerOrInfinity](https://tc39.es/ecma262/#sec-tointegerorinfinity).