Make pixel projection handling work in compiled mode

The compiler seems to have trouble with functions that can run with
different 'this' types. By moving the units handling to the callback, this
issue can be avoided.

src/ol/featureloader.js

@@ -104,18 +104,9 @@ ol.featureloader.loadFeaturesXhr = function(url, format, success, failure) {
                   goog.asserts.fail('unexpected format type');
                 }
                 if (source) {
-                  if (ol.ENABLE_VECTOR_TILE && this instanceof ol.VectorTile) {
-                    var dataUnits = format.readProjection(source).getUnits();
-                    if (dataUnits === ol.proj.Units.TILE_PIXELS) {
-                      projection = new ol.proj.Projection({
-                        code: this.getProjection().getCode(),
-                        units: dataUnits
-                      });
-                      this.setProjection(projection);
-                    }
-                  }
                   success.call(this, format.readFeatures(source,
-                      {featureProjection: projection}));
+                      {featureProjection: projection}),
+                      format.readProjection(source));
                 } else {
                   goog.asserts.fail('undefined or null source');
                 }
@@ -147,9 +138,18 @@ ol.featureloader.tile = function(url, format) {
   return ol.featureloader.loadFeaturesXhr(url, format,
       /**
        * @param {Array.<ol.Feature>} features The loaded features.
+       * @param {ol.proj.Projection} dataProjection Data projection.
        * @this {ol.VectorTile}
        */
-      function(features) {
+      function(features, dataProjection) {
+        var dataUnits = dataProjection.getUnits();
+        if (dataUnits === ol.proj.Units.TILE_PIXELS) {
+          var projection = new ol.proj.Projection({
+            code: this.getProjection().getCode(),
+            units: dataUnits
+          });
+          this.setProjection(projection);
+        }
         this.setFeatures(features);
       },
       /**
@@ -174,9 +174,10 @@ ol.featureloader.xhr = function(url, format) {
   return ol.featureloader.loadFeaturesXhr(url, format,
       /**
        * @param {Array.<ol.Feature>} features The loaded features.
+       * @param {ol.proj.Projection} dataProjection Data projection.
        * @this {ol.source.Vector}
        */
-      function(features) {
+      function(features, dataProjection) {
         this.addFeatures(features);
       }, /* FIXME handle error */ ol.nullFunction);
 };

src/ol/vectortile.js

@@ -161,6 +161,7 @@ ol.VectorTile.prototype.load = function() {
 
 /**
  * @param {Array.<ol.Feature>} features Features.
+ * @api
  */
 ol.VectorTile.prototype.setFeatures = function(features) {
   this.features_ = features;