GF-60177: Spotlight disappear routine in rc6 doesn't work in some case

Reproduce
1. run DisappearSample.html
2. click "destroy my ancestor" button.

Expected
- spotlight moves to "I am default ..." button

Result
- spotlight is disappeared.

Solution
- we can solve this difference by checking oControl.destroyed or change
getAbsoluteShowing of control.js to check destroy property also.
Merge pull request #102 from enyojs/GF-60177-kunmyonchoi

GF-60177: Spotlight disappear routine in rc6 doesn't work in some case