BHV-14856: Guard against uncreated DOM node. Also, optimization to prevent repeated calculation of popup bounds.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>
Merge pull request #1646 from enyojs/BHV-14856-aarontam

BHV-14856: Guard against uncreated DOM node. Also, optimization to prevent repeated calculation of popup bounds