Fix the bug that layers got updated in the middle of the picking cycle (#458)
Fix the bug that layers got updated in the middle of the picking cycle (#458)

* Fix the bug that layers got updated in the middle of the picking cycle
* Much more detailed comments
* Check whether info is empty before put it to info map
* Remove redundant checking info against null after the above check

uber-common/deck.gl,uber-common/deck.gl