ANG-4775: Use enyo.perfNow instead of enyo.now()

enyo.perfNow is independent of system clock changing.
It is also safer for using in animation.

Enyo-DCO-1.1-Signed-off-by: David Um david.um@lge.com
ANG-4775: Resolve dead rock status in animation playing

If animation is trapped in infinite loop, it make animation finish.

Enyo-DCO-1.1-Signed-off-by: David Um david.um@lge.com
Replace undefined to null to clear timeout handle for duration check.

DCO-1.1-Signed-Off-By: Kunmyon Choi <kunmyon.choi@lge.com>
Merge pull request #1214 from enyojs/ANG-4775-davidum

ANG-4775: Use enyo.perfNow instead of enyo.now on StyleAnimator and check duration to make sure animation ends