fix #408

Former-commit-id: 9ca7540bcc2b72862ad87ee3f1f6ff0cba33db4e

lib/single-file/processors/hooks/content/content-hooks-frames-web.js

@@ -296,6 +296,7 @@
 			observers.set(intersectionObserver, { callback, options });
 			return intersectionObserver;
 		};
+		window.IntersectionObserver.prototype = IntersectionObserver.prototype;
 		window.IntersectionObserver.toString = function () { return "function IntersectionObserver() { [native code] }"; };
 	}