WTS: Continuation of ef7ea1e5: set onSOL in handleSeparatorText

* Run "ISBN length" test in --wt2wt --trace wts mode before and
  after this patch to see the changes in state.onSOL flag.

Change-Id: I790d4700b5155c2d90cac0cbaf729feb12036458
Merge "WTS: Continuation of ef7ea1e5: set onSOL in handleSeparatorText"