Hey developers, I don't know whether or not you all know this, but PNACL and NACL are being phased out in 2018. I know that this is what Lichess uses for local computer analysis. More details:https://developer.chrome.com/native-client/migration
Lichess has a WebAssembly version of Stockfish already (it's used in Firefox). All it needs is for WebAssembly to support multiple threads, which should hopefully happen some time before the PNACL phase-out.