BHV-11655: Replace for in to for on DataList.js

### Issue:
"For in" only can be used properly on hash but in this case it is used with Array which is having prototype functions.

### Fix:
Replace "for in" to "for"

DCO-1.1-Signed-Off-By: Kunmyon Choi kunmyon.choi@lge.com
You can assign pages.length to 'var l' like for (var p=0, l=pages.length; p< l; p++)