add absoluteShowing api to Control and default value support to computed properties

Enyo-DCO-1.1-Signed-Off-By: Cole Davis (cole.davis@lge.com)
update bad test cases and change api for es5 compliance

Enyo-DCO-1.1-Signed-Off-By: Cole Davis (cole.davis@lge.com)
Merge pull request #616 from enyojs/absolute-showing-cole-davis

Absolute showing API - required for fix for GF-57676

Reviewed-By: Ben Combee (ben.combee@lge.com)