Make unicodeAccents.js ES6 module (#1477)

Use `babel-register` in `unicodeMake.js` to require ES6 module.

src/unicodeAccents.js

@@ -1,9 +1,6 @@
 // Mapping of Unicode accent characters to their LaTeX equivalent in text and
 // math mode (when they exist).
-
-// NOTE: This module needs to be written with Node-style modules (not
-// ES6 modules) so that unicodeMake.js (a Node application) can import it.
-module.exports = {
+export default {
     '\u0301': {text: "\\'", math: '\\acute'},
     '\u0300': {text: '\\`', math: '\\grave'},
     '\u0308': {text: '\\"', math: '\\ddot'},

src/unicodeMake.js

@@ -5,7 +5,8 @@
 // In this way, only this tool, and not the distribution/browser,
 // needs String's normalize function.
 
-const accents = require('./unicodeAccents');
+require('babel-register')({plugins: ["transform-es2015-modules-commonjs"]});
+const accents = require('./unicodeAccents').default;
 
 console.log("// @flow");
 console.log("// This file is GENERATED by unicodeMake.js. DO NOT MODIFY.");