### Platforms affected
iOS
### What does this PR do?
fix issue[ #340](https://github.com/apache/cordova-plugin-inappbrowser/issues/340) iOS CDVWKInAppBrowser evaluateJavascript method randomly gets blocked on iOS 12
### What testing has been done on this change?
manual testing
### Checklist
- [x] [Reported an issue](http://cordova.apache.org/contribute/issues.html) in the JIRA database
- [x] Commit message follows the format: "CB-3232: (android) Fix bug with resolving file paths", where CB-xxxx is the JIRA ID & "android" is the platform affected.
- [ ] Added automated test coverage as appropriate for this change.
