I couldn't clearly figure that out myself. I only know that they are interconnected somehow (or supposed to be), but `unresolved/resolved` didn't do anything for me, while `polymer-veiled/polymer-unveil` (note how the second one is not `polymer-veil**ed**`) did -- but the problem was that the switch from one to the other was applied too soon by the Polymer, not prevention FOUC at all.