Merge branch 'master' into devtools-v4-merge

Author: Brian Vaughn

package.json

@@ -4,6 +4,7 @@
     "packages/*"
   ],
   "devDependencies": {
+    "@babel/plugin-syntax-jsx": "^7.2.0",
     "@babel/cli": "^7.0.0",
     "@babel/code-frame": "^7.0.0",
     "@babel/core": "^7.0.0",

packages/babel-plugin-react-jsx/README.md

@@ -0,0 +1,5 @@
+This package is intended to eventually replace the current `@babel/plugin-transform-react-jsx`, changing the JSX transform from targeting `React.createElement(type, props, children)` to `React.jsx(types, props, key)`. 
+
+https://github.com/reactjs/rfcs/blob/createlement-rfc/text/0000-create-element-changes.md
+
+**This is experimental and not intended to be used directly.**