Use Message::text instead of relying on Message::_toString

Previously they were being ->parse()'d, however none of the messages
require parsing so text is fine. Also switched some Html::rawElement's to
Html::element's for extra safety.

Change-Id: I600b16f5c163aa74b5a9feed9948f718d1ce7239
Merge "Use Message::text instead of relying on Message::_toString"