iOS Magnifying glass is showing bottom layer

# Bug Report
When long press on the content to trigger the magnifying glass to show content (such as select input, etc.), the content shown is not the webpage from the inappbrowser, but rather the bottom index.html.

## Problem
When long press on the content to trigger the magnifying glass to show content (such as select input, etc.), the content shown is not the webpage from the inappbrowser, but rather the bottom index.html.

### What is expected to happen?
Showing the content rendered in the inappbrowser

### What does actually happen?
Showing the content from the bottom index.html.

## Information

My index.html has a static splashscreen, and the index.js triggers a cordova.InAppBrowser.open to open up the url I would use.

### Command or Code

### Environment, Platform, Device

Environment: iOS
Platform: iOS
Device: iPhone 5 through iPhone Xs

### Version information

Checked with two versions of Cordova iOS (4.5.5 and 5.0.0) as well as two versions of inappbrowser (3.0.0 and 3.1.0-dev), the issue still exists.

I understand there're issues for this https://issues.apache.org/jira/browse/CB-12875 and seems like it was marked resolve, but unfortunately I don't think that fix is for this issue, as 3.1.0-dev (current master branch) still have this issue.

## Checklist

- [x] I searched for existing GitHub issues
- [x] I updated all Cordova tooling to most recent version
- [x] I included all the necessary information above

Start by reproducing the long-press magnifying-glass behavior on iOS using the index.html splash screen and the index.js call to cordova.InAppBrowser.open, comparing it with the displayed in-app browser content. Done means the magnifying glass shows the webpage rendered in the InAppBrowser instead of the bottom index.html across the reported iPhone devices.

Written by the indexing model from the issue text.