Add unreleased changelog

CHANGELOG.md

@@ -1,3 +1,34 @@
+## [Unreleased]
+<details>
+  <summary>
+    Changes that have landed in master but are not yet released.
+    Click to see more.
+  </summary>
+
+### React
+
+* You can now assign `propTypes` to components returned by `React.ForwardRef`. ([@bvaughn](https://github.com/bvaughn) in [#12911](https://github.com/facebook/react/pull/12911))
+
+### React DOM
+
+* Fix a crash when the input `type` changes from some other types to `text`. ([@spirosikmd](https://github.com/spirosikmd) in [#12135](https://github.com/facebook/react/pull/12135))
+* Fix a crash in IE11 when restoring focus to an SVG element. ([@ThaddeusJiang](https://github.com/ThaddeusJiang) in [#12996](https://github.com/facebook/react/pull/12996))
+* Fix a range input not updating in some cases. ([@Illu](https://github.com/Illu) in [#12939](https://github.com/facebook/react/pull/12939))
+* Fix input validation triggering unnecessarily in Firefox. ([@nhunzaker](https://github.com/nhunzaker) in [#12925](https://github.com/facebook/react/pull/12925))
+* Fix an incorrect `event.target` value for the `onChange` event in IE9. ([@nhunzaker](https://github.com/nhunzaker) in [#12976](https://github.com/facebook/react/pull/12976))
+* Fix a false positive error when returning an empty `<React.Fragment />` from a component. ([@philipp-spiess](https://github.com/philipp-spiess) in [#12966](https://github.com/facebook/react/pull/12966))
+
+### React DOM Server
+
+* Fix an incorrect value being provided by new context API. ([@ericsoderberghp](https://github.com/ericsoderberghp) in [#12985](https://github.com/facebook/react/pull/12985), [@gaearon](https://github.com/gaearon) in [#13019](https://github.com/facebook/react/pull/13019))
+
+### React Test Renderer
+
+* Allow multiple root children in test renderer traversal API. ([@gaearon](https://github.com/gaearon) in [#13017](https://github.com/facebook/react/pull/13017))
+* Fix `getDerivedStateFromProps()` in the shallow renderer to not discard the pending state. ([@fatfisz](https://github.com/fatfisz) in [#13030](https://github.com/facebook/react/pull/13030))
+
+</details>
+
 ## 16.4.0 (May 23, 2018)
 
 ### React