Remove goog.asserts.*

This pull requests replaces type check hint assertions with type casts,
library sanity check assertions with conditional console.assert statements
in debug mode, and runtime sanity checks with assertions that throw an
ol.AssertionError with an error code for lookup outside the library.

src/ol/style/style.js

@@ -1,6 +1,5 @@
 goog.provide('ol.style.Style');
 
-goog.require('goog.asserts');
 goog.require('ol.geom.Geometry');
 goog.require('ol.geom.GeometryType');
 goog.require('ol.style.Circle');
@@ -159,20 +158,13 @@ ol.style.Style.prototype.setGeometry = function(geometry) {
     this.geometryFunction_ = geometry;
   } else if (typeof geometry === 'string') {
     this.geometryFunction_ = function(feature) {
-      var result = feature.get(geometry);
-      if (result) {
-        goog.asserts.assertInstanceof(result, ol.geom.Geometry,
-            'feature geometry must be an ol.geom.Geometry instance');
-      }
-      return result;
+      return /** @type {ol.geom.Geometry} */ (feature.get(geometry));
     };
   } else if (!geometry) {
     this.geometryFunction_ = ol.style.defaultGeometryFunction;
   } else if (geometry !== undefined) {
-    goog.asserts.assertInstanceof(geometry, ol.geom.Geometry,
-        'geometry must be an ol.geom.Geometry instance');
     this.geometryFunction_ = function() {
-      return geometry;
+      return /** @type {ol.geom.Geometry} */ (geometry);
     };
   }
   this.geometry_ = geometry;
@@ -211,8 +203,8 @@ ol.style.createStyleFunction = function(obj) {
     if (Array.isArray(obj)) {
       styles = obj;
     } else {
-      goog.asserts.assertInstanceof(obj, ol.style.Style,
-          'obj geometry must be an ol.style.Style instance');
+      ol.assert(obj instanceof ol.style.Style,
+          41); // Expected an `ol.style.Style` or an array of `ol.style.Style`
       styles = [obj];
     }
     styleFunction = function() {
@@ -343,6 +335,6 @@ ol.style.createDefaultEditingStyles = function() {
  * @return {ol.geom.Geometry|ol.render.Feature|undefined} Geometry to render.
  */
 ol.style.defaultGeometryFunction = function(feature) {
-  goog.asserts.assert(feature, 'feature must not be null');
+  ol.DEBUG && console.assert(feature, 'feature must not be null');
   return feature.getGeometry();
 };