Work around compiler not detecting implementation of abstract methods

src/ol/view.js

@@ -47,13 +47,21 @@ ol.View.prototype.getHints = function() {
 /**
  * @inheritDoc
  */
-ol.View.prototype.getView2D = goog.abstractMethod;
+ol.View.prototype.getView2D = function() {
+  // FIXME for some reason, we can't use goog.abstractMethod here
+  goog.asserts.fail();
+  return null;
+};
 
 
 /**
  * @inheritDoc
  */
-ol.View.prototype.getView3D = goog.abstractMethod;
+ol.View.prototype.getView3D = function() {
+  // FIXME for some reason, we can't use goog.abstractMethod here
+  goog.asserts.fail();
+  return null;
+};
 
 
 /**