app freeze/unresponsive if closed without pressing close button

# Bug Report
App freezes/becomes unresponsive if the in app browser is closed by swiping down instead of hitting the Close button.

## Problem
### What is expected to happen?
I would expect swiping down to have the same result as pressing the Close button and the app to continue to work as normal.

### What does actually happen?
App becomes unresponsive, nothing in the UI works, there are no errors thrown or logs shown. Force killing the app resolves the issue.

## Information

I'm using _blank for the in app modal, and usewkwebview=yes. Pulling latest master 80feff6cf8e3def9bdd388e56d6cb2dbb44a2d2c fixes the in app browser not showing up (issue in 3.1.0) but there is still an issue with swiping the browser modal away, which will not work as expected. I have tried various forks and updating other packages but have not been able to resolve.

### Command or Code

Open in app browser, when closing, instead of pressing Close button (which works), swipe the modal down to dismiss it. The UI becomes unresponsive afterward.

### Environment, Platform, Device

iOS 13.

### Version information

"cordova": "^8.1.2",
"cordova-ios": "^5.0.0",
"cordova-plugin-ionic-keyboard": "^2.1.3",
"cordova-plugin-wkwebview-engine": "^1.1.4",
"cordova-plugin-wkwebviewxhrfix": "git+https://github.com/TheMattRay/cordova-plugin-wkwebviewxhrfix.git",
"cordova-plugin-inappbrowser": "git+https://github.com/apache/cordova-plugin-inappbrowser.git",
...

## Checklist

- [x] I searched for existing GitHub issues
Similar to https://github.com/apache/cordova-plugin-inappbrowser/issues/426 but doesn't seem to be the same issue.
- [ ] I updated all Cordova tooling to most recent version
I'm not able to update all the tooling atm.
- [x] I included all the necessary information above

Reproduce on iOS 13 by opening the in-app browser with _blank and usewkwebview=yes, then dismiss it by swiping rather than pressing Close. Compare both dismissal paths and inspect the plugin behavior involved; done means swipe dismissal leaves the app UI responsive without requiring a force quit.

Written by the indexing model from the issue text.