generate-changelog.js should be Node 6 compatible

Summary:
Node on SandCastle is ancient, this change makes sure we can use the node version of `www`.

Node 6 can't parse dangling comma's in argument lists, which is what prettier automatically inserts by fbsource standards

Reviewed By: passy

Differential Revision: D20366026

fbshipit-source-id: 1b2a0c1506e8671fa268fab7a8d3bfcd5064bb0b

.eslintignore

@@ -11,3 +11,4 @@ lib
 dist
 website/build
 react-native/ReactNativeFlipperExample
+scripts/generate-changelog.js

scripts/generate-changelog.js

@@ -5,7 +5,12 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @format
+ * @noformat
+ */
+
+/**
+ * WARNING: this file should be able to run on node v6.16.0, which is used at SandCastle.
+ * Please run `nvm use 6.16.0` before testing changes in this file!
  */
 
 const path = require('path');
@@ -14,9 +19,7 @@ const cp = require('child_process');
 
 const root = path.join(__dirname, '..');
 
-const version = JSON.parse(
+const version = JSON.parse(fs.readFileSync(path.join(root, 'package.json'), 'utf8')).version;
-  fs.readFileSync(path.join(root, 'package.json'), 'utf8'),
-).version;
 
 const now = new Date();
 const date = `${now.getDate()}/${now.getMonth() + 1}/${now.getFullYear()}`;
@@ -29,12 +32,12 @@ const lastCommit = cp
 const firstCommit = cp
   .execSync(
     `hg log --limit 1 --template '{node}' --keyword 'Flipper Release: v'`,
-    {cwd: root},
+    {cwd: root}
   )
   .toString();
 
 console.log(
-  `Generating changelog for version ${version} based on ${firstCommit}..${lastCommit}`,
+  `Generating changelog for version ${version} based on ${firstCommit}..${lastCommit}`
 );
 
 // # get all commit summaries since last release | find all changelog entries, but make sure there is only one line per commit by temporarily replacing newlines