Fix tdz checks in transform-block-scoping plugin (#9498)

* Better tdz tests

- Use jest's expect.toThrow/expect.not.toThrow
- Add input/output tests

* Fix basic tdz (a = 2; let a)

Fixes #6848

* Make _guessExecutionStatusRelativeTo more robust

* Add tests

* Return less "unkown" execution status

* "function" execution status does not exist

* Fix recursive functions

* Update helper version

* "finally" blocks are always executed

* Typo

packages/babel-traverse/src/path/inference/inferer-reference.js

@@ -102,7 +102,7 @@ function getConstantViolationsBefore(binding, path, functions) {
   return violations.filter(violation => {
     violation = violation.resolve();
     const status = violation._guessExecutionStatusRelativeTo(path);
-    if (functions && status === "function") functions.push(violation);
+    if (functions && status === "unknown") functions.push(violation);
     return status === "before";
   });
 }