The WebConsoleFrame
stuff was ported to the add-on SDK loader in bug 877262.
Judging from the code, the following should give access to the WebConsoleFrame
the add-on "uses":
var {devtools} = Cu.import("resource://gre/modules/devtools/Loader.jsm", {});
var {WebConsoleFrame} = devtools.require("devtools/webconsole/webconsole");
As for the second part of your question: Will the devtools support the same stuff natively?
I'm not sure. You should get in touch with the devtools team and ask them and have a look at the existing bugs: Open devtools bugs containing "json". And/or file a new enhancement bug.