I thought the problem was with `AssignmentDeclarationKind.ThisProperty`. Why is the new code in `None` instead? Is it because there's an existing PropertyDeclaration? The new code in `getSymbolForExpression` kind of looks like it's a fallback mode for when syntactic detection fails in the checker, which it shouldn't if it has succeeded in the binder. So maybe the fix needs to be to iron out some mismatch between the binder and checker.