SQLite WebAssembly micro-benchmark and new build with a memory leak fix (#70)

lib/sql-js/benchmark/Dockerfile

@@ -0,0 +1,19 @@
+FROM node:12-buster
+
+RUN set -ex; \
+    echo 'deb http://deb.debian.org/debian unstable main' \
+        > /etc/apt/sources.list.d/unstable.list; \
+    apt-get update; \
+    apt-get install -y -t unstable firefox; \
+    apt-get install -y chromium
+
+WORKDIR /tmp/build
+
+COPY package.json ./
+COPY lib/dist lib/dist
+COPY lib/package.json lib/package.json
+RUN npm install
+
+COPY . .
+
+CMD npm run benchmark