package/ci: use Emscripten 1.37.1 instead of 1.37.10.

The newer version crashes, probably just a random breakage. Will wait
until it improves.

package/ci/travis.yml

@@ -126,7 +126,9 @@ install:
 - if [ "$TRAVIS_OS_NAME" == "linux" ] && [ "$TARGET" == "android" ]; then wget -nc http://dl.google.com/android/ndk/android-ndk-r10e-linux-x86_64.bin && chmod +x android-*.bin && ./android-*.bin -y | grep -v Extracting; fi
 - if [ "$TRAVIS_OS_NAME" == "osx" ] && [ "$TARGET" == "desktop" ]; then export PLATFORM_GL_API=CGL; fi
 - if [ "$TRAVIS_OS_NAME" == "osx" ] && [ "$TARGET" == "ios-simulator" ]; then gem install xcpretty; fi
-- if [ "$TRAVIS_OS_NAME" == "osx" ] && [ "$TARGET" == "emscripten" ]; then brew install emscripten && export LLVM=/usr/local/opt/emscripten/libexec/llvm/bin && emcc; fi
+# Emscripten 1.37.10 is broken (crashes during optimization), using 1.37.1
+# works. Replace with just `brew install emscripten` when sane again
+- if [ "$TRAVIS_OS_NAME" == "osx" ] && [ "$TARGET" == "emscripten" ]; then brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/53f53f6498ba0f507c443dd4f0c6217937f1ddf2/Formula/emscripten.rb && export LLVM=/usr/local/opt/emscripten/libexec/llvm/bin && emcc; fi
 - if [ "$TARGET" == "desktop" ] || [ "$TARGET" == "desktop-sanitizers" ] || [ "$TARGET" == "desktop-gles" ]; then printf "[General]\ndrivers=null" > ~/.alsoftrc; fi
 
 # SDL (cached)