Ran the checker on a couple larger projects, but no real-world reports found so far (same as DeleteWithNonVirtualDtor). Can't tell if it's an engine limitation or just the bug being uncommon in general.

Replaced backticks with single quotes.

@steakhal gentle ping for one last round of reviews

Updated the visitor to track all conversions, and have type names for clarity.

Added a test for taking last upcast only for the note tag. For now the visitor matches all explicit casts, because there are too many edge cases to count for now wrt. explicit upcasting.

Fixed the formatting issues as well.

Refactored the checkers to use a shared base class, otherwise I kept the same functionality.

Indeed it would make more sense to separate checkers into their own classes, but using a shared base. This checker doesn't have quite as advanced logic as MallocChecker, so there's not that much of a need for a single class managing everything. I'll change the checker to that system.