13: retain leading comments when replacing the imports

test/fixtures/comments.input.js

@@ -0,0 +1,61 @@
+/*
+* top of file
+*/
+'use strict';
+// after use strict
+var a = 'a';
+/*
+* after var a
+*/
+
+// before foo
+// const foo = 123;
+// after foo
+
+// before other imports
+// import Funk from 'funky-town';
+// after other imports
+
+// All comments between an expression and import React should remain.
+
+// before blah
+// const blah = 111;
+// after blah
+
+// before react import
+import React, {
+  Platform,
+  NativeModules,
+} from 'react-native';
+// after imports
+
+// before Spaghetti
+import Spaghetti from 'food';
+// after Spaghetti
+
+/**
+* comment above class
+*/
+export default class Foo extends React.Component {
+  static get propTypes() {
+    return {};
+    // bottom of propTypes
+  }
+
+  // above componentWillMount
+  componentWillMount() {}
+
+  /**
+  * multi-line comment above foo
+  * @param {String} blah
+  * @return {undefined}
+  */
+  foo(blah) {}
+
+  render() {
+    // top of render
+    return;
+  }
+}
+
+// EOF

test/fixtures/comments.output.js

@@ -0,0 +1,61 @@
+/*
+* top of file
+*/
+'use strict';
+// after use strict
+var a = 'a';
+
+/*
+* after var a
+*/
+
+// before foo
+// const foo = 123;
+// after foo
+
+// before other imports
+// import Funk from 'funky-town';
+// after other imports
+
+// All comments between an expression and import React should remain.
+
+// before blah
+// const blah = 111;
+// after blah
+
+// before react import
+import React from 'react';
+
+import {Platform, NativeModules} from 'react-native';
+// after imports
+
+// before Spaghetti
+import Spaghetti from 'food';
+// after Spaghetti
+
+/**
+* comment above class
+*/
+export default class Foo extends React.Component {
+  static get propTypes() {
+    return {};
+    // bottom of propTypes
+  }
+
+  // above componentWillMount
+  componentWillMount() {}
+
+  /**
+  * multi-line comment above foo
+  * @param {String} blah
+  * @return {undefined}
+  */
+  foo(blah) {}
+
+  render() {
+    // top of render
+    return;
+  }
+}
+
+// EOF

transform.js

@@ -231,6 +231,7 @@ export default function(file, api, options) {
       ))
     }
 
+    allImports[0].comments = path.node.comments;
     j(path).replaceWith(
       allImports
     );