upgrade typescript to 4.7.4

[kainino0x]

Not entirely clear why upgrading caused type narrowing to fail in these
cases, but it's easy to fix.

Issue: none

---

Requirements for PR author:

• All missing test coverage is tracked with "TODO" or .unimplemented().
• New helpers are /** documented */ and new helper files are found in helper_index.txt.
• Test behaves as expected in a WebGPU implementation. (If not passing, explain above.)

Requirements for reviewer sign-off:

• Tests are properly located in the test tree.
• Test descriptions allow a reader to "read only the test plans and evaluate coverage completeness", and accurately reflect the test code.
• Tests provide complete coverage (including validation control cases). Missing coverage MUST be covered by TODOs.
• Helpers and types promote readability and maintainability.

When landing this PR, be sure to make any necessary issue status updates.

[kainino0x]

@shaoboyan PTAL

[github-actions]

Previews, as seen when this build job started (9dc8a48):
Run tests | View tsdoc

[shaoboyan]

Thanks for upgrading and happy to remove requestVideoFrameCallback declare