Register var decls generated by import ... = TS transform

[amoeller]

Q	A
Fixed Issues?	Fixes #15486
Patch: Bug Fix?
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/54109/

[JLHwung]

The transform part looks good to me. Left comments on testing.

[JLHwung]

If we are visiting the foo identifier, we can assert that the scope has registered binding:

expect(path.scope.hasBinding(path.node.name)).toBe(true);

At the end of the traversal, we can assert that the assertion must have been tested:

{
  visitor: {
    Program: {
      exit() {
        expect.assertions(1)
      }
   }
}

So that if the structure of input.js is changed, this test will not silently pass because the identifier visitor is not invoked.

[nicolo-ribaudo]

Thank you!

[nicolo-ribaudo]

(I'll fix the failing test locally before merging)