firebase 4.1.2

on Node.js Yarn

Fixes

• Fixed an issue where sourcemaps weren't pointing to the actual
  Typescript source code. #29
• Fixed an issue where FirebaseAppImpl.prototype was being incorrectly
  patched. #38
• Fixed an issue where loading the SDK from our CDN, while also
  providing a chunked webpack build, was duplicating the webpackJsonp
  namespace. #43