WebUI: Replace uglifyjs with uglify-es which understands ES6.

chrome/browser/resources/vulcanize_gn.py

 #!/usr/bin/env python
 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import argparse
 import itertools
 import os
 import platform
 import re
@@ skipping 170 matching lines @@
     with open(html_out_path, 'r+') as f:
       data = f.read()
       new_data = data.replace(
           '</body></html>',
           '<script src="' + args.js_out_file + '"></script></body></html>')
       assert new_data != data, 'Expected to find </body></html> token.'
       f.seek(0)
       f.write(new_data)
       f.truncate()
 
-    node.RunNode([node_modules.PathToUglifyJs(), crisper_output.name,
+    node.RunNode([node_modules.PathToUglify(), crisper_output.name,
                   '--comments', '"/Copyright|license|LICENSE|\<\/?if/"',
                   '--output', js_out_path])
   finally:
     if os.path.exists(crisper_input.name):
       os.remove(crisper_input.name)
     if os.path.exists(crisper_output.name):
       os.remove(crisper_output.name)
 
 
 def main(argv):
@@ skipping 15 matching lines @@
   args.depfile = os.path.normpath(args.depfile)
   args.input = os.path.normpath(args.input)
   args.out_folder = os.path.normpath(args.out_folder)
 
   _vulcanize(args.input, args)
   _update_dep_file(args.input, args)
 
 
 if __name__ == '__main__':
   main(sys.argv[1:])