Travis tests failing running binaryen.js

[sbc100]

e.g https://travis-ci.org/WebAssembly/binaryen/jobs/524300394

building shared bitcode
shared:WARNING: not all asm.js optimizations are possible with ALLOW_MEMORY_GROWTH, disabling those. [-Walmost-asm]
building binaryen.js
shared:WARNING: not all asm.js optimizations are possible with ALLOW_MEMORY_GROWTH, disabling those. [-Walmost-asm]
error: undefined symbol: $FS
warning: To disable errors for undefined symbols use `-s ERROR_ON_UNDEFINED_SYMBOLS=0`
Error: Aborting compilation due to previous errors
shared:ERROR: '/emsdk_portable/node/bin/node /emsdk_portable/sdk/src/compiler.js /tmp/tmp6XnMu_.txt /emsdk_portable/sdk/src/library_pthread_stub.js' failed (1)
The command "docker exec -it emscripten bash ./travis-emcc-tests.sh" exited with 1.

I guess this is due to recent emscripten changes.

[kripken]

Yeah, should be fixed by the landing of emscripten-core/emscripten#8464 (but CI may not immediately pick that up).