Skip wit-bindgen install on emscripten builder

Author: kateinoigakukun

builders/wasm32-unknown-emscripten/Dockerfile

@@ -1,14 +1,5 @@
-FROM rust:1.57-buster as wit-bindgen-builder
-
-ARG WIT_BINDGEN_REV=dab589f579b980c81b39c8348400b88a8c4d175a
-RUN cargo install --git https://github.com/bytecodealliance/wit-bindgen \
-  --rev $WIT_BINDGEN_REV \
-  --root /tmp/install wit-bindgen-cli
-
 FROM emscripten/emsdk:2.0.13
 
-COPY --from=wit-bindgen-builder /tmp/install/bin/wit-bindgen /usr/local/bin/wit-bindgen
-
 RUN set -eux; \
   apt-get update; \
   apt-get install ruby bison make autoconf git curl -y; \