Use the node:10-alpine issue (mozilla#263)

The `node:latest` image that was being used is too variable and
broke things when it moved to Node 11.

Fix mozilla#262

Author: pmac

bin/build.sh

@@ -3,5 +3,5 @@ cd "$(dirname ${BASH_SOURCE[0]})"/..
 
 docker run --rm --label=node \
     -v $(pwd):/app -w /app\
-    node \
+    node:10-alpine \
     npm run-script build