Computing FOLLOW sets of left recursive grammar
The cited algorithm for FIRST and FOLLOW  is a least fixed-point algorithm; recursive inclusion of the same set is a no-op.
That's clearly stated in the Dragon Book's description of this algorithm, which involves repeatedly evaluating  the equations until no additional elements are added to any set during an iteration.
The algorithm works without the necessity to remove left recursion (and recursive equations in the FOLLOW set are possible without left recursion in the grammar). Left recursion elimination is not isomorphic, by the way; it's not a reversible procedure and the original grammar can not be recovered.