Close unclosed HTML p-tags on encountering a block token

* Found roundtrip regressions on eswiki/Departamento_del_Litoral
  which I traced to RT diffs on the simplified test case:
  '<div><p>foo</div>\na\n\nb'. The parse output was incorrect
  on this snippet where the unclosed p-tag affected p-wrapping
  down the line.

* This patch fixes that by closing open HTML p-tags at block-tag
  boundaries.

* Added the above snippet as a new parser test.

* Fixes RT regressions on eswiki/Departamento_del_Litoral and
  hewiki/מבצע_עופרת_יצוקה

Change-Id: Ia54fcf6afb541f0e6fe8a946b53f9490fff6b8ec
Fix for crashers in RT testing.

* Standard crasher we've run into many times
 (checking for missing tsr).

* Now frwiki/Morthomiers?oldid=98196163 parses without crashing.

Change-Id: If339aa33195e47e8ba667c709859cca81dd7edfa