Can't post messages to iframes

[jvitela]

The MessageDispatcher only contains code to post messages to window.parent and window.parent.frames, but if the React application creates one or more iframes it would need to send a message using something like this

const frames = document.getElementsByTagName('iframe');
for (let i = 0; i < frames.length; i++) {    
    frames[i].contentWindow.postMessage(data, senderOrigin);
}