BHV-11657: Make addBodyClass to see the length of enyo.roots to know whether it is rendered.

### Issue
enyo-locale-right-to-left is not set on the body of apps.

### Fix

Latest commit is initializing roots as array which resulting return true on enyo.exists which is not intended result.
https://github.com/enyojs/enyo/commit/76e44bc3f1caf45fb060e7da16a62f1d500ede88
So, adding array length check on addBodyClass to address this problem.

DCO-1.1-Signed-Off-By: Kunmyon Choi kunmyon.choi@lge.com
Merge pull request #799 from enyojs/BHV-11657-kunmyonchoi

BHV-11657: Make addBodyClass to see the length of enyo.roots to know whe...

Looks good!

Reviewed-by: Aaron Tam (aaron.tam@lge.com)