Adds Node and Firebase tools.

Dockerfile

@@ -1,5 +1,16 @@
 FROM circleci/android:api-29
 
 USER root
+
+# Skip checking SSH host keys.
 RUN mkdir /root/.ssh && chmod 700 /root/.ssh
-RUN /bin/echo -e "Host github.com\n\tStrictHostKeyChecking no\n" >> /root/.ssh/config
+RUN /bin/echo -e "Host github.com\n\tStrictHostKeyChecking no\n" >> /root/.ssh/config
+
+# Install Node
+RUN apt-get install -y curl \
+  && curl -sL https://deb.nodesource.com/setup_9.x | bash - \
+  && apt-get install -y nodejs \
+  && curl -L https://www.npmjs.com/install.sh | sh
+
+# install Firebase CLI
+RUN npm install -g firebase-tools