BHV-6685: Adjust z-index of DataGridList item when spotted/unspotted.

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>
Minor method change for naming consistency.
Enyo-DCO-1.1-Signed-off-by: Blake Stephens <blake.stephens@lge.com>
Merge pull request #1264 from enyojs/BHV-6685-aarontam

BHV-6685: Adjust z-index of DataGridList item when spotted/unspotted.