Strip about and typeof attributes from expected HTML output in parserTests

We strip these from our HTML output as the expected output of HTML parser
tests does not contain these attributes. We have now added some
Parsoid-specific parser tests whose expected HTML output includes about and
typeof attributes, but these fail as typeof and about is stripped from our
output. So strip the about and typeof from expected output too.

This makes one more wt2html test pass. Hooray ;)

Change-Id: I86838ebc2b7655e90a21baf232c4ddfb8bbbb54c