Update emscripten version

Emscripten and rustc have to use compatible versions of LLVM to avoid
linker error. With the update to LLVM 11, emscripten also requires an
update, see rust-lang/rust#75716.

Also, now the emscripten is updated, the fix for
emscripten-core/emscripten#4542 is now avalibe, which
means we can delete the node-wasm workaround.

Signed-off-by: Joe Richey <joerichey@google.com>

docker/Dockerfile.asmjs-unknown-emscripten

@@ -9,7 +9,7 @@ RUN /cmake.sh
 COPY xargo.sh /
 RUN /xargo.sh
 
-COPY --from=trzeci/emscripten:1.38.46-upstream /emsdk_portable /emsdk_portable
+COPY --from=trzeci/emscripten:1.39.20-upstream /emsdk_portable /emsdk_portable
 
 ENV EMSDK /emsdk_portable
 ENV EMSCRIPTEN=${EMSDK}/emscripten/sdk

docker/Dockerfile.wasm32-unknown-emscripten

@@ -9,7 +9,7 @@ RUN /cmake.sh
 COPY xargo.sh /
 RUN /xargo.sh
 
-COPY --from=trzeci/emscripten:1.38.46-upstream /emsdk_portable /emsdk_portable
+COPY --from=trzeci/emscripten:1.39.20-upstream /emsdk_portable /emsdk_portable
 
 ENV EMSDK /emsdk_portable
 ENV EMSCRIPTEN=${EMSDK}/emscripten/sdk
@@ -27,5 +27,4 @@ RUN apt-get update && apt-get install --assume-yes --no-install-recommends \
   libxml2 \
   python
 
-COPY node-wasm /usr/local/bin/
-ENV CARGO_TARGET_WASM32_UNKNOWN_EMSCRIPTEN_RUNNER=node-wasm
+ENV CARGO_TARGET_WASM32_UNKNOWN_EMSCRIPTEN_RUNNER=node