browser extension binaries are cached in the emsdk image to simplify testing

scripts/bash/build_emscripten_image.sh

@@ -10,6 +10,7 @@ EMSDK_VERSION=${1:-"4.0.1"}
 export DOCKER_BUILDKIT=1
 
 docker build --target=supplemented_emscripten_builder \
+  --progress=plain \
   --build-arg "EMSCRIPTEN_VERSION=${EMSDK_VERSION}" \
-  --tag "${REGISTRY}emsdk:${EMSDK_VERSION}-2" \
+  --tag "${REGISTRY}emsdk:${EMSDK_VERSION}-3" \
   --file "${SRCDIR}/Dockerfile.emscripten" "${SRCDIR}"