Prepare Release of polymer-cli 1.9.9 and polymer-build 3.1.4 (#3407)

* Updated CHANGELOG, package.json and package-lock.json files for release of build + cli
* Updated goldens because dependency update included *fix* to es5 code-- "function"===typeof Symbol changed to "undefined"===typeof Symbol in a check.

Author: usergenic

package-lock.json

@@ -5,10 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
-## Unreleased
-* Fixed an issue where bare specifiers were not rewritten for dynamic imports after transforming them to AMD require statements.
+<!-- ## Unreleased -->
 <!-- Add new, unreleased changes here. -->
 
+## [3.1.4] - 2019-04-26
+* Fixed an issue where bare specifiers were not rewritten for dynamic imports after transforming them to AMD require statements.
+
 ## [3.1.3] - 2019-04-02
 * Disabled `babel-plugin-minify-builtins` and `babel-plugin-minify-remove-undefined` due to errors in `babel-preset-minify`.