Changelog for 16.9 (facebook#16254)

* Changelog for 16.9 (TODO: add date)

* Update CHANGELOG.md

* Add date

CHANGELOG.md

@@ -6,6 +6,41 @@
   </summary>
 </details>
 
+## 16.9.0 (August 8, 2019)
+
+### React
+
+* Add `<React.Profiler>` API for gathering performance measurements programmatically. ([@bvaughn](https://github.com/bvaughn) in [#15172](https://github.com/facebook/react/pull/15172))
+* Remove `unstable_ConcurrentMode` in favor of `unstable_createRoot`. ([@acdlite](https://github.com/acdlite) in [#15532](https://github.com/facebook/react/pull/15532))
+
+### React DOM
+
+* Deprecate old names for the `UNSAFE_*` lifecycle methods. ([@bvaughn](https://github.com/bvaughn) in [#15186](https://github.com/facebook/react/pull/15186) and [@threepointone](https://github.com/threepointone) in [#16103](https://github.com/facebook/react/pull/16103))
+* Deprecate `javascript:` URLs as a common attack surface. ([@sebmarkbage](https://github.com/sebmarkbage) in [#15047](https://github.com/facebook/react/pull/15047))
+* Deprecate uncommon "module pattern" (factory) components. ([@sebmarkbage](https://github.com/sebmarkbage) in [#15145](https://github.com/facebook/react/pull/15145))
+* Add support for the `disablePictureInPicture` attribute on `<video>`. ([@eek](https://github.com/eek) in [#15334](https://github.com/facebook/react/pull/15334))
+* Add support for `onLoad` event for `<embed>`. ([@cherniavskii](https://github.com/cherniavskii) in [#15614](https://github.com/facebook/react/pull/15614))
+* Add support for editing `useState` state from DevTools. ([@bvaughn](https://github.com/bvaughn) in [#14906](https://github.com/facebook/react/pull/14906))
+* Add support for toggling Suspense from DevTools. ([@gaearon](https://github.com/gaearon) in [#15232](https://github.com/facebook/react/pull/15232))
+* Warn when `setState` is called from `useEffect`, creating a loop. ([@gaearon](https://github.com/gaearon) in [#15180](https://github.com/facebook/react/pull/15180))
+* Fix a memory leak. ([@paulshen](https://github.com/paulshen) in [#16115](https://github.com/facebook/react/pull/16115))
+* Fix a crash inside `findDOMNode` for components wrapped in `<Suspense>`. ([@acdlite](https://github.com/acdlite) in [#15312](https://github.com/facebook/react/pull/15312))
+* Fix pending effects from being flushed too late. ([@acdlite](https://github.com/acdlite) in [#15650](https://github.com/facebook/react/pull/15650))
+* Fix incorrect argument order in a warning message. ([@brickspert](https://github.com/brickspert) in [#15345](https://github.com/facebook/react/pull/15345))
+* Fix hiding Suspense fallback nodes when there is an `!important` style. ([@acdlite](https://github.com/acdlite) in [#15861](https://github.com/facebook/react/pull/15861) and [#15882](https://github.com/facebook/react/pull/15882))
+* Slightly improve hydration performance. ([@bmeurer](https://github.com/bmeurer) in [#15998](https://github.com/facebook/react/pull/15998))
+
+### React DOM Server
+
+* Fix incorrect output for camelCase custom CSS property names. ([@bedakb](https://github.com/bedakb) in [#16167](https://github.com/facebook/react/pull/16167))
+
+### React Test Utilities and Test Renderer
+
+* Add `act(async () => ...)` for testing asynchronous state updates. ([@threepointone](https://github.com/threepointone) in [#14853](https://github.com/facebook/react/pull/14853))
+* Add support for nesting `act` from different renderers. ([@threepointone](https://github.com/threepointone) in [#16039](https://github.com/facebook/react/pull/16039) and [#16042](https://github.com/facebook/react/pull/16042))
+* Warn in Strict Mode if effects are scheduled outside an `act()` call. ([@threepointone](https://github.com/threepointone) in [#15763](https://github.com/facebook/react/pull/15763) and [#16041](https://github.com/facebook/react/pull/16041))
+* Warn when using `act` from the wrong renderer. ([@threepointone](https://github.com/threepointone) in [#15756](https://github.com/facebook/react/pull/15756))
+
 ## 16.8.6 (March 27, 2019)
 
 ### React DOM