Issues with frames and postMessage

[brettz9]

I'm using PhantomJS with Karma and running into some issues using postMessage on frames.

Note that I'm already handling the need for appending base/ to my URLs as per issue #14119, so it is not that the URLs are a problem.

Here are the following idiosyncrasies I've observed:

1. The iframe is actually somehow loaded to show logging before the parent frame which dynamically loads it. I don't know whether this may have some partial bearing on the behaviors below.
2. Although Firefox had, at least at one point, implemented this behavior, postMessage
   should not post messages to all windows (including itself) at the designated origin, but only to the window on which postMessage is called (incidentally, I think the old way was much cooler, but the spec doesn't support this and Chrome doesn't either). In the case of PhantomJS, I am not able to successfully post a message on my iframe's contentWindow, and sometimes the child frame can post on parent but sometimes not. I can work around this by having a window post to itself, but again, this is not standard.

[stale]

Due to our very limited maintenance capacity, we need to prioritize our development focus on other tasks. Therefore, this issue will be automatically closed (see #15395 for more details). In the future, if we see the need to attend to this issue again, then it will be reopened. Thank you for your contribution!