Currently, when `HTMLEditor` replaces text in a text node, `HTMLEditor`
creates a set of `DeleteTextTransaction` and `InsertTextTransaction`.
However, this has bad impact for footprint and causes the callers messy.
This patch creates `ReplaceTextTransaction` instead and
`HTMLEditor::ReplaceTextWithTransaction()` as its wrapper. Unfortunately,
this becomes not calling `nsIEditActionListener::DidDeleteText()`, however,
this is not used by mozilla-central, comm-central nor BlueGriffon. IIRC,
it was not removed for some legacy addons of Thunderbird. Therefore, it
must be okay to remove it.
Differential Revision: https://phabricator.services.mozilla.com/D76078
Masayuki Nakano