tools: prepare tools/js2c.py for Python 3

PR-URL: nodejs#24798
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

Author: cclauss

tools/js2c.py

@@ -37,6 +37,11 @@
 import string
 import hashlib
 
+try:
+    xrange          # Python 2
+except NameError:
+    xrange = range  # Python 3
+
 
 def ToCArray(elements, step=10):
   slices = (elements[i:i+step] for i in xrange(0, len(elements), step))