Allow passing undefined to ol.layer.Vector#setStyle
Better docs for ol.layer.Vector#setStyle
Support nullable params and returns in generated externs
Merge pull request #2645 from ahocevar/nullable-externs

Support nullable params and returns in generated externs
Merge pull request #2638 from elemoine/setstyle

Allow passing undefined to ol.layer.Vector#setStyle
Upgrade closure-library version
Add missing goog.require