Add a noop function as the default for onSearch
Add a noop function as the default for onSearch

This way we can safely call this.props.onSearch('') when closing the
menu regardless of whether the parent component actually supports
searching, although there might be a cleaner way to handle this.

unicef/polio,unicef/rhizome,SeedScientific/polio,SeedScientific/polio,unicef/rhizome,unicef/rhizome,unicef/polio,unicef/rhizome,SeedScientific/polio,SeedScientific/polio,SeedScientific/polio,unicef/polio,unicef/polio