Cannot use greenlet in node. TypeError: URL.createObjectURL is not a function

I am trying to use greenlet in an isomorphic application, where the code will be run in browser and server. I am struggling to use it in node, where I keep getting `TypeError: URL.createObjectURL is not a function`.

I have tried the following polyfill but no luck.

```
global.Worker = require('tiny-worker')
global.Blob = require('cross-blob')
global.URL = require('url-polyfill')
```

What should I do to run greenlet in node?

Start by reproducing the Node error with greenlet and the listed tiny-worker, cross-blob, and url-polyfill setup. Trace the worker initialization that calls URL.createObjectURL; done means the isomorphic application can run greenlet in Node without this TypeError.

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