add npm install to emscripten Makefile
add npm install to emscripten Makefile

romanz/trezor-crypto,jhoenicke/trezor-crypto,trezor/trezor-crypto,trezor/trezor-crypto,runn1ng/trezor-crypto,romanz/trezor-crypto,trezor/trezor-crypto,jhoenicke/trezor-crypto,jhoenicke/trezor-crypto,romanz/trezor-crypto,runn1ng/trezor-crypto,romanz/trezor-crypto,jhoenicke/trezor-crypto,jhoenicke/trezor-crypto,romanz/trezor-crypto,runn1ng/trezor-crypto,trezor/trezor-crypto,trezor/trezor-crypto,runn1ng/trezor-crypto,runn1ng/trezor-crypto