This callback is only used in very limited ways, so just require that the
caller passes in the canonical supports pointer plus the participant.
This probably won't affect performance much.
The nsISupports objects added to the purple buffer are already canonical,
so we can avoid some overhead by not QIing them to
`nsCycleCollectionISupports`.
Since these are just interpreted comments, there's 0 impact on actual code.
This removes all lines that match /* vim: set(.*)tw=80: */ with S&R -- there are
a few others scattered around which will be removed manually in a second part.
This creates a number of stubs and leaves some surrounding code that may be irrelevant (eg. recorded time stamps, status variables).
Stub resolution/removal should be a follow-up to this.
