Add ol.array.safeExtend
Use ol.array.safeExtend in ol.geom.LineString
Use ol.array.safeExtend in ol.geom.MultiLineString
Use ol.array.safeExtend in ol.geom.MultiPoint
Use ol.array.safeExtend in ol.geom.MultiPolygon
Use ol.array.safeExtend in ol.geom.Polygon
Use ol.array.safeExtend in ol.format.GML
Use ol.array.safeExtend in ol.format.KML