Add ol.Map#isRendered

src/ol/map.js

@@ -1010,6 +1010,14 @@ ol.Map.prototype.isDef = function() {
 };
 
 
+/**
+ * @return {boolean} Is rendered.
+ */
+ol.Map.prototype.isRendered = function() {
+  return !goog.isNull(this.frameState_);
+};
+
+
 /**
  * Render.
  */