Preserve jsx comment (#7155)

packages/babel-generator/src/generators/jsx.js

@@ -91,7 +91,9 @@ export function JSXClosingElement(node: Object) {
   this.token(">");
 }
 
-export function JSXEmptyExpression() {}
+export function JSXEmptyExpression(node: Object) {
+  this.printInnerComments(node);
+}
 
 export function JSXFragment(node: Object) {
   this.print(node.openingFragment, node);

packages/babel-generator/test/fixtures/jsx/comments/actual.js

@@ -0,0 +1,13 @@
+class Demo extends React.Component {
+  constructor(props) {
+    super(props);
+    this.state = {};
+  }
+  render() {
+    return <div>
+      <Dialog>
+        {/*<div>I am a jsx comment!!</div>*/}
+      </Dialog>
+    </div>;
+  }
+}

packages/babel-generator/test/fixtures/jsx/comments/expected.js

@@ -0,0 +1,17 @@
+class Demo extends React.Component {
+  constructor(props) {
+    super(props);
+    this.state = {};
+  }
+
+  render() {
+    return <div>
+      <Dialog>
+        {
+          /*<div>I am a jsx comment!!</div>*/
+        }
+      </Dialog>
+    </div>;
+  }
+
+}

packages/babel-generator/test/fixtures/jsx/comments/options.json

@@ -0,0 +1 @@
+{ "plugins": ["jsx"] }