Because of spurious flow it is possible that the preds of the try-begin
block are not the only blocks that can dominate a handler. We handled
this possibility, but only for finally/fault blocks that can directly
have these edges. However, even other handler blocks can be reachable
through spurious paths that involves finally/fault blocks, and in these
cases returning the preds of the try-begin block is not enough to
compute the right dominator statically.