Leave sol-transparent tags out of p-wrappers where possible

* Followup to 920c4b07 -- seems natural to leave sol-transparent
  tags out. This fix also improves parser test results in an
  unrelated p-wrapper patch which is coming later.

* Additional html2html test passing, and 3 more selser tests
  seem to be green.

Change-Id: I9bd782598d81ad7a230a033aef20960181735e81