@firebase/polyfill(latest: 0.3.36) This is the a set of polyfills/shims used by the Firebase JS SDK. This package is completely standalone and can be loaded to standardize environments for use with the Firebase JS SDK.
@firebase/webchannel-wrapper(latest: 0.6.1) A wrapper of the webchannel packages from closure-library for use outside of a closure compiled application
@firebase/util(latest: 1.4.3) _NOTE: This is specifically tailored for Firebase JS SDK usage, if you are not a member of the Firebase team, please avoid using this package_