Add TypeScript declarations

javascript/sources/sync.asmjs.js

@@ -4,14 +4,10 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @flow
  * @format
  */
 
-const wrapLib = require('./entry');
+const wrapAsm = require('./wrapAsm');
 const loadYoga = require('./asmjs-sync');
 
-module.exports = wrapLib(loadYoga());
-
-export type * from './YGEnums.js';
-export type * from './entry';
+module.exports = wrapAsm(loadYoga());