message: Prepare 4.0.0-pre.4 release.
diff: @@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
  <!-- ## Unreleased -->
  <!-- Add new, unreleased changes here. -->
  +
  +## 4.0.0-pre.4 - 2018-04-02
  +- Fix issue where external script tags referencing bundled ES modules were not updated.
  +
  ## 4.0.0-pre.3 - 2018-03-28
  - [BREAKING] The `--in-html` and `--out-html` arguments for `bin/polymer-bundler` are now `--in-file` and `--out-file` because input filetypes are no longer limited to HTML.
  - ES6 Module Bundling! Bundler can simultaneously process HTML imports and ES6 module imports, including inline `<script type="module">` scripts.
  