Update hmr.ts

[xrgaddtt2]

This is to fix the bug that if the hmrPort != port, a server is not started on the hmrPort and HMR doesn't work

Changes

If the server is supplied it is not checking to see whether the hmrPort is different to the server port. If it is different, a new server needs to be started on the HMR port. Supplying null to her-server-enngine will cause it to start a new server on that port

Testing

tested locally with hmrPort!=port, works correctly

Docs

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Latest commit: cb76d4e

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