Int.construct(from:) can crash instead of return nil #258

While the JSValueCompatible APIs are failable, the underlying conversion of calling SignedInteger.init(_:) and UnsignedInteger.init(_:) directly can crash at runtime if:

• double.isNan
• !double.isFinite
• double > .max || double < .min

Ideally, none of these would crash and return nil instead:

• Int.construct(from: JSValue.number(.infinity))
• Int.construct(from: JSValue.number(.nan))
• Int.construct(from: JSValue.number(numberGreaterThanIntMax)
• Int.construct(from: JSValue.number(numberLessThanIntMin)