Account for null or undefined geometry

The change in #2098 made it so a feature's geometry could be undefined.  This is consistent with the return type for the getGeometry method.  Where calling code needs to ensure that it has a geometry instance, it can use instanceof, goog.isDefAndNotNull(), or test for a truthy value.

src/ol/interaction/draganddropinteraction.js

@@ -115,7 +115,7 @@ ol.interaction.DragAndDrop.prototype.handleResult_ = function(file, result) {
       for (j = 0, jj = readFeatures.length; j < jj; ++j) {
         var feature = readFeatures[j];
         var geometry = feature.getGeometry();
-        if (!goog.isNull(geometry)) {
+        if (goog.isDefAndNotNull(geometry)) {
           geometry.applyTransform(transform);
         }
         features.push(feature);