Performance/stability feature: WASM handling of revocation list size

[bumblefudge]

As mentioned in #339 , in WASM reqwest can't effectively check the size of a revocation list effectively, falling back to the HTTP headers which could be inaccurate. one solution would be to wait for reqwest to merge a native feature: https://github.com/seanmonstar/reqwest/issues/1234 (^ But that's been open without a PR since april...)