Add 15.4.2 changelog

Author: gaearon

CHANGELOG.md

@@ -1,3 +1,26 @@
+## 15.4.2 (January 6, 2017)
+
+### React
+
+* Fixed build issues with the Brunch bundler. ([@gaearon](https://github.com/gaearon) in [#8686](https://github.com/facebook/react/pull/8686))
+
+* Improved error messages for invalid element types. ([@spicyj](https://github.com/spicyj) in [#8612](https://github.com/facebook/react/pull/8612))
+
+* Removed a warning about `getInitialState` when `this.state` is set. ([@bvaughn](https://github.com/bvaughn) in [#8594](https://github.com/facebook/react/pull/8594))
+
+* Removed some dead code. ([@diegomura](https://github.com/diegomura) in [#8050](https://github.com/facebook/react/pull/8050), [@dfrownfelter](https://github.com/dfrownfelter) in [#8597](https://github.com/facebook/react/pull/8597))
+
+### React DOM
+
+* Fixed rendering of textarea placeholder in IE11. ([@aweary](https://github.com/aweary) in [#8020](https://github.com/facebook/react/pull/8020))
+
+* Worked around a script engine bug in IE9. ([@eoin](https://github.com/eoin) in [#8018](https://github.com/facebook/react/pull/8018))
+
+### React Addons
+
+* Fixed build issues in RequireJS and SystemJS environments. ([@gaearon](https://github.com/gaearon) in [#8686](https://github.com/facebook/react/pull/8686))
+* Added missing package dependencies. ([@kweiberth](https://github.com/kweiberth) in [#8467](https://github.com/facebook/react/pull/8467))
+
 ## 15.4.1 (November 22, 2016)
 
 ### React