We've recently decided that we want to "extend" comments until
the end of the paragraph (e36dc8e78a,
d0ae6c4e44).
However, we still had this special case that did the opposite: it
ensured that if a comment ended in the middle of a text node, the
comment would not be extended to the end of the node. Remove it.
Note the change in the test file signatures-funny-formattedreply.html,
which actually covered this case specifically.
Change-Id: Id1384bb0c6e1a5f0c70f55efcb4caa240f230f07
0fc71f60cd