function filterByPrefix( out, arr, str ) {
	var i;
	for ( i = 0; i < arr.length; i++ ) {
		if ( startsWith( arr[ i ], str ) ) {
			out.push( arr[ i ] );
		}
	}
	return out;
}
Filters a list of strings based on a provided search string.

@private
@param {Array} out - output array
@param {Array} arr - source array
@param {string} str - string filter
@returns {Array} output array