They run through completely different logic as only handshake is fragmented.
This'll make it easier to rewrite the handshake logic in a follow-up.
Change-Id: I9515feafc06bf069b261073873966e72fcbe13cb
Reviewed-on: https://boringssl-review.googlesource.com/6420
Reviewed-by: Adam Langley <agl@google.com>