feat(wasm): support "pure JS" mode

Closes #1159

This uses the binaryen tool wasm2js to compile the Anubis WASM blobs
to JavaScript. This produces biblically large (520Ki) outputs when you
inline both hashx and sha256 solvers, but this is a tradeoff that I'm
willing to accept. The performance is good enough in my testing with
JIT enabled. I fear that this may end up being terrible with JIT
disabled. I have no idea if this will work on big endian or not.

Signed-off-by: Xe Iaso <me@xeiaso.net>

scripts/build_wasm.sh

@@ -1,5 +1,7 @@
 #!/usr/bin/env bash
 
+set -euo pipefail
+
 mkdir -p ./web/static/wasm/{simd128,baseline}
 
 cargo clean
@@ -12,4 +14,11 @@ cargo clean
 
 # Without simd128
 cargo build --release --target wasm32-unknown-unknown
-cp -vf ./target/wasm32-unknown-unknown/release/*.wasm ./web/static/wasm/baseline
+cp -vf ./target/wasm32-unknown-unknown/release/*.wasm ./web/static/wasm/baseline
+
+for file in ./web/static/wasm/baseline/*.wasm; do
+  echo $file
+  rm -f ${file%.*}.wasmjs
+  wasm2js $file -all -O4 --strip-debug --rse --rereloop --optimize-for-js --flatten --dce --dfo --fpcast-emu --denan --dealign --remove-imports --remove-unused-names --remove-unused-brs --reorder-functions --reorder-locals --strip-target-features --untee --vacuum -s 4 -ffm -lmu -tnh -iit -n -o ${file%.*}.mjs
+  sed -i '1s$.*$const anubis_update_nonce = (_ignored) => { };$' ${file%.*}.mjs
+done