basis.ui.field: cleanup combobox code
basis.ui.field: cleanup combobox code

tyanas/basisjs,tyanas/basisjs,fateevv/basisjs,basisjs/basisjs,fateevv/basisjs,tyanas/basisjs,smelukov/basisjs,istrel/basisjs,istrel/basisjs,basisjs/basisjs,istrel/basisjs,smelukov/basisjs,fateevv/basisjs,smelukov/basisjs,basisjs/basisjs