RemoveUnusedBrs: Avoid an error on loops with unreachable ifs (#7156)

We normally like to move brs after ifs into the if, when in a loop:

(loop $loop
  (if
    ..
    (unreachable)
    (code)
  )
  (br $loop)
)

=>

(loop $loop
  (if
    ..
    (unreachable)
    (block
      (code)
      (br $loop) ;; moved in
    )
  )
)

However this may be invalid to do if the if condition is unreachable, as
then one arm may be concrete (`code` in the example could be an `i32`,
for example). As this is dead code anyhow, leave it for DCE.

0 files changed, 0 insertions, 0 deletions