Grow scan_stack in the conventional direction

The pretty printer algorithm involves 2 VecDeques: a ring-buffer of
tokens and a deque of ring-buffer indices. Confusingly, those two deques
were being grown in opposite directions for no good reason. Ring-buffer
pushes would go on the "back" of the ring-buffer (i.e. higher indices)
while scan_stack pushes would go on the "front" (i.e. lower indices).
This commit flips the scan_stack accesses to grow the scan_stack and
ring-buffer in the same direction, where push does the same
operation as a Vec push i.e. inserting on the high-index end.

0 files changed, 0 insertions, 0 deletions