Apply content wrapping in ParserOutput::getText()

Apply content wrapping in ParserOutput::getText()

Instead of applying wrapping the the parser and unwrapping in
ParserOutput::getText(), turn this around and apply wrapping in getText(),
and only if desired.

This avoids search&replace logic for unwrapping, and it also makes it a lot
easier to merge the output of multiple slots for MCR output.

This changes behavior in two hopefully irrelevant ways:
1) the limit report comments will be inside the wrapper div, instead of
following it.
2) if HTML with a wrapper div is explicitly injected into a ParserOutput
object, it will not be possible to unwrap the text.

Bug: T174035
Change-Id: I1641b7995af9bd297f1acd610d583fbf874f34e0