Make file inherit from blob

# Bug Report

## Problem
```js
console.assert(file instanceof Blob)
```
should not show a error

### What is expected to happen?
File should inherit from Blob and not show a error

### What does actually happen?
it logs a error, file is not a instance of Blob

## Information
- https://github.com/webtorrent/create-torrent/pull/89
- https://stackoverflow.com/questions/56787344/error-the-first-argument-must-be-a-file-or-blob-object/56791566#56791566

## Checklist

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

---

I'm not a cordova developer but i tried it out a long time ago... it's not really my issue but someone else

No source file or test is named in the issue. Start by locating the plugin's JavaScript File implementation and reproduce the reported `file instanceof Blob` assertion; done means File inherits from Blob without the error and the relevant regression coverage passes.

Written by the indexing model from the issue text.