Adding a data-mw-parsoid-version attribute to the wrapper div helps to
unambiguously mark parsoid-generated output in a way which is compatible
with CSS rules and client-side JavaScript.
By embedding the current version of parsoid in the data attribute,
sophisticated CSS rules can match against a specific version of
Parsoid in order to facilitate proper behavior; for example:
div[data-mw-parsoid-version^="0.20.0"]
This could be useful in deployment scenarios where the parser cache
might contain content generated by older or newer versions of Parsoid,
for roll-forward or roll-back deployment scenarios, respectively.
Bug: T363378
Change-Id: I941d31479eebb12ea1f4dcdb0a1737033ddc8ac1
7738554eee