Backport #28441 by wxiaoguang
Fix #28319
It only polyfills if there is no "SubmitEvent" class, so it has no side
effect for most users.
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
WIP because:
- [x] Some calls set a `content-type` but send no body, can likely
remove the header
- [x] Need to check whether `charset=utf-8` has any significance on the
webauthn calls, I assume not as it is the default for json content.
- [x] Maybe `no-restricted-globals` is better for eslint, but will
require a lot of duplication in the yaml or moving eslint config to a
`.js` extension.
- [x] Maybe export `request` as `fetch`, shadowing the global.