removeJavaScriptHandler method
Removes a JavaScript message handler previously added with the addJavaScriptHandler associated to handlerName key.
Returns the value associated with handlerName before it was removed.
Returns null if handlerName was not found.
Implementation
@override
Function? removeJavaScriptHandler({required String handlerName}) {
return this._javaScriptHandlersMap.remove(handlerName);
}