InAppBrowser will not destroy WebView after being closed (by invoking ref.close()) causing memory leaks

On both Android and iOS, ref.close() does not close the window. I can see the webview is still running. Does not seem to be specific to device or OS. However, I have been testing on iPhone X, with iOS 11.4.1 as well as Samsung S5 running Android 6.0.1.

Start by reproducing ref.close() on the tested Android and iOS devices, then trace how the InAppBrowser WebView is closed on each platform. Done means closing the window destroys or stops the WebView and prevents the reported memory leak on both platforms.

Written by the indexing model from the issue text.