Introduce tile-pixels units

src/ol/geom/geometry.js

@@ -2,10 +2,12 @@ goog.provide('ol.geom.Geometry');
 goog.provide('ol.geom.GeometryLayout');
 goog.provide('ol.geom.GeometryType');
 
+goog.require('goog.asserts');
 goog.require('goog.functions');
 goog.require('ol.Object');
 goog.require('ol.extent');
 goog.require('ol.proj');
+goog.require('ol.proj.Units');
 
 
 /**
@@ -250,6 +252,9 @@ ol.geom.Geometry.prototype.translate = goog.abstractMethod;
  * @api stable
  */
 ol.geom.Geometry.prototype.transform = function(source, destination) {
+  goog.asserts.assert(
+      ol.proj.get(source).getUnits() !== ol.proj.Units.TILE_PIXELS,
+      'cannot transform geometries with TILE_PIXELS units');
   this.applyTransform(ol.proj.getTransform(source, destination));
   return this;
 };