Fix flow errors.

.flowconfig

@@ -8,3 +8,5 @@ suppress_comment=\\(.\\|\n\\)*\\$FlowFixMe\\($\\|[^(]\\|(\\(>=0\\.\\(3[0-9]\\|[1
 suppress_comment=\\(.\\|\n\\)*\\$FlowIssue\\((\\(>=0\\.\\(3[0-9]\\|[1-2][0-9]\\|[0-9]\\).[0-9]\\)? *\\(site=[a-z,_]*react_native_fb[a-z,_]*\\)?)\\)?:? #[0-9]+
 suppress_comment=\\(.\\|\n\\)*\\$FlowFixedInNextDeploy
 suppress_comment=\\(.\\|\n\\)*\\$FlowExpectedError
+
+unsafe.enable_getters_and_setters=true

packages/setupBabel.js

@@ -0,0 +1,50 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+'use strict';
+
+const babelRegisterOnly = require('./metro-bundler/babelRegisterOnly');
+const escapeRegExp = require('lodash/escapeRegExp');
+const path = require('path');
+
+const BABEL_ENABLED_PATHS = [
+  'metro-bundler/src',
+  'metro-bundler/transformer.js',
+  'metro-bundler/react-packager.js',
+];
+
+/**
+ * We use absolute paths for matching only the top-level folders reliably. For
+ * example, we would not want to match some deeply nested forder that happens to
+ * have the same name as one of `BABEL_ENABLED_PATHS`.
+ */
+function buildRegExps(basePath, dirPaths) {
+  return dirPaths.map(folderPath =>
+    // Babel `only` option works with forward slashes in the RegExp so replace
+    // backslashes for Windows.
+    new RegExp(`^${escapeRegExp(path.resolve(basePath, folderPath).replace(/\\/g, '/'))}`)
+  );
+}
+
+function getOnlyList() {
+  return buildRegExps(__dirname, BABEL_ENABLED_PATHS);
+}
+
+/**
+ * Centralized place to register all the directories that need a Babel
+ * transformation before being fed to Node.js. Notably, this is necessary to
+ * support Flow type annotations.
+ */
+function setupBabel() {
+  babelRegisterOnly(getOnlyList());
+}
+
+setupBabel.buildRegExps = buildRegExps;
+setupBabel.getOnlyList = getOnlyList;
+module.exports = setupBabel;