don't make config key change and size change conflict

Use a single timer instead of two and use flags for events that can
lead to a relayout. the flags at the moment are size change and config
key for serialization change.

if they happen in the same moment (for instance when the serialization
config key is dependent from the size) if the new key already is saved
consider it correct and don't try to keep the distance to screen edges
from the old layout, ruining the saved one

CCBUG:360478