Add ol.style.Circle#getHitDetectionImage

src/ol/style/circlestyle.js

@@ -69,6 +69,14 @@ ol.style.Circle.prototype.getImage = function(pixelRatio) {
 };
 
 
+/**
+ * @inheritDoc
+ */
+ol.style.Circle.prototype.getHitDetectionImage = function(pixelRatio) {
+  return this.canvas_;
+};
+
+
 /**
  * @inheritDoc
  */