Provide default value to result method. Fix #1495

- Do not provide default value to result fallback. Check for membership when evaluating result default value for existing objects
- Check for property membership with in. Add result test for prototypes
- Result should use the fallback for methods that are undefined
- Add a test to confirm fallback is not used in result if result of function is undefined
- Use void 0
Merge pull request #1515 from nhunzaker/master

Provide default value to result method. Fix #1495