Webworker Headers missing entries()

[13rac1]

Worker Header interface is missing the entries() method:
https://developer.mozilla.org/en-US/docs/Web/API/Headers/entries

The Headers.entries() method returns an iterator allowing to go through all key/value pairs contained in this object. The both the key and value of each pairs are ByteString objects.

Problem is probably due to it being worker only.

Note: This method is available in Web Workers.

It's not listed in the fetch.widl https://github.com/microsoft/TSJS-lib-generator/blob/a20c41802d11d47dbe27b09f0ad2c9f47a3db421/inputfiles/idl/Fetch.widl#L3-L12

Requires changes to inputfiles/overridingTypes.json to implement.

[saschanaz]

This is because we don't have webworker.iterable.generated.d.ts. We should create it.