fix(#169): Replace installFetch() with installPolyfills()

[pham]

Summary

Replace src/files/shims.js with the polyfills version.

Fixes: #169

[jthegedus]

Thanks

[eXodes]

@jthegedus Hi James, is this going to be merged anytime soon?

[koreypeters-dexcom]

Would love to see this merged as well.

[Nushio]

Hi Pham,

I've tested your changes on my sveltekit project and it's working fine. I also went ahead and fixed the integration tests that are currently failing, but I'm not sure how to push the commit onto this PR.
Nushio@d356444

I'd like to release the latest version of svelte-adapter-firebase with my fixes on Windows, your polyfills change, and co3k's header's pr (with a minor fix) as version 0.15.0 this week, if there are no objections / issues.

[pham]

Hi Pham,

I've tested your changes on my sveltekit project and it's working fine. I also went ahead and fixed the integration tests that are currently failing, but I'm not sure how to push the commit onto this PR. Nushio@d356444

I'd like to release the latest version of svelte-adapter-firebase with my fixes on Windows, your polyfills change, and co3k's header's pr (with a minor fix) as version 0.15.0 this week, if there are no objections / issues.

Nushio,
If you'd create a pull request on my fork with your changes, I'll merge it and hopefully, that will get updated here.

[Nushio]

Done!
pham#2

[Nushio]

Looks good to me.