Revert "Fixed the reverse algorithm for Sass 3.3"

This reverts commit de27ad2240e8d36243228b58338fb791c03fe437.

The "for" loop, starting from 1, needs to end at 1 or a greater index.

When length($list) was 0, floor(length($list)/2) evaluated to 0.
Fixed by setting an offset of +1.