Upgrade React to 16.8.4: Welcome React Hooks (#14400)

lib/client-assets.php

@@ -380,10 +380,21 @@ function gutenberg_register_scripts_and_styles() {
  * @since 0.1.0
  */
 function gutenberg_register_vendor_scripts() {
-	/*
-	 * This function is kept as an empty stub, in case Gutenberg should need to
-	 * explicitly provide a version newer than that provided by core.
-	 */
+	$suffix = SCRIPT_DEBUG ? '' : '.min';
+
+	// Vendor Scripts.
+	$react_suffix = ( SCRIPT_DEBUG ? '.development' : '.production' ) . $suffix;
+
+	gutenberg_register_vendor_script(
+		'react',
+		'https://unpkg.com/react@16.8.4/umd/react' . $react_suffix . '.js',
+		array( 'wp-polyfill' )
+	);
+	gutenberg_register_vendor_script(
+		'react-dom',
+		'https://unpkg.com/react-dom@16.8.4/umd/react-dom' . $react_suffix . '.js',
+		array( 'react' )
+	);
 }
 
 /**

package.json

@@ -106,8 +106,9 @@
 		"pegjs": "0.10.0",
 		"phpegjs": "1.0.0-beta7",
 		"postcss": "7.0.13",
-		"react-dom": "16.6.3",
-		"react-test-renderer": "16.6.3",
+		"react": "16.8.4",
+		"react-dom": "16.8.4",
+		"react-test-renderer": "16.8.4",
 		"redux": "4.0.0",
 		"rimraf": "2.6.2",
 		"rtlcss": "2.4.0",