Fewer bitwise operators

The way left shift [is used](https://github.com/openlayers/ol3/blob/4c2463dd91bc9c112a2a404cf7ddbb66a15543b2/src/ol/tilecoord.js#L45) [in](https://github.com/openlayers/ol3/blob/4c2463dd91bc9c112a2a404cf7ddbb66a15543b2/src/ol/source/tilejsonsource.js#L115) [some](https://github.com/openlayers/ol3/blob/4c2463dd91bc9c112a2a404cf7ddbb66a15543b2/src/ol/source/bingmapssource.js#L100) [places](https://github.com/openlayers/ol3/blob/4c2463dd91bc9c112a2a404cf7ddbb66a15543b2/src/ol/source/xyzsource.js#L67), we'll get good behavior with ~31 zoom levels.  This may be acceptable for popular xyz layers.  The way left shift [is used](https://github.com/openlayers/ol3/blob/4c2463dd91bc9c112a2a404cf7ddbb66a15543b2/src/ol/tilegrid/tilegrid.js#L337) to [calculate](https://github.com/openlayers/ol3/blob/4c2463dd91bc9c112a2a404cf7ddbb66a15543b2/src/ol/view2d.js#L59) [resolutions](https://github.com/openlayers/ol3/blob/4c2463dd91bc9c112a2a404cf7ddbb66a15543b2/src/ol/tilegrid/xyztilegrid.js#L22), we only get 23 levels with the default tile size.  This is an unnecessary restriction.