28spin, if this is the only file missing, you can try to upload it manually from the 1.1.6 full release. Just extract the following file from the 1.1.6 archive and upload it to your server in the corresponding directory:
If this does not work, try to run the upgrade again via SSH:
./pear mage-setup .
./pear install -f magento-core/Mage_All_Latest-stable
It will force an upgrade to the latest version and hopefully replace any missing/broken files.