Update cherry-picked LESSFunctions.php to final ResourceLoaderFunctions.php

Brings cherry-picked I9785a601fd5d57c9d8d84b90ee29eef61a6f2e77 up to date
with the final merged version of 11eb53abbc5ab3bf1ca5d60cf6adacd897860d3a

Change-Id: Icbaf77293951b89790a799cb9d3235c607902165
Merge "Update cherry-picked LESSFunctions.php to final ResourceLoaderFunctions.php" into wmf/1.22wmf19