chakrashim: switch var to let and const

PR-URL: #476
Reviewed-By: Jack Horton <Jack.Horton@microsoft.com>
Reviewed-By: Taylor Woll <tawoll@ntdev.microsoft.com>
Reviewed-By: Seth Brenith <sethb@microsoft.com>
Reviewed-By: Jimmy Thomson <jithomso@microsoft.com>

Author: kfarnung