[FileAPI] Blob.close() has several problems (#10)

Not defined what happens with `b` in

```js
a = new Blob(...)
b = new Blob([a])
a.close()
```

Probably it should not be closed.

We need to define how this affects other specifications such as `FormData`, `XMLHttpRequest`, etc.

If `blob.close()` revokes URLs it needs to be defined how that happens. Are the URLs stored on the instance?

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/FileAPI/issues/10