fetching .wasm does not work behind proxy

[recro-lataille]

Im using HA proxy for ssl termination with client certificate validation. the fetch for f8f821a66b20e5801e35df5ec4565b30.wasm (onigasm I believe) fails this was reproduced in the firefox browser by using the console fetch('f8f821a66b20e5801e35df5ec4565b30.wasm') the solution was tested by doing fetch('f8f821a66b20e5801e35df5ec4565b30.wasm', {credentials: 'same-origin') and the fetch is successful.

Steps to Reproduce

1. ssl terminating load balance validating client certs
2. load the codeserver on the browser

[code-asher]

Closing per comments in #846.