issue with reading scientific notation coordinates in ol.format.GML

For example:

```
                <gml:Point srsDimension="2" srsName="http://www.opengis.net/gml/srs/epsg.xml#3857">
                    <gml:pos>-1.153568815095287E7 5539267.516059847</gml:pos>
                </gml:Point>
```