fix: remove outdated TODOs in runtime code

[chenjiahan]

Summary

Remove the TODOs in the runtime code, because:

• The TODO was originally added in 2022, and the current runtime code seems to be the same as webpack, so the TODO should be unnecessary now.
• The runtime code will be bundled with the user code, when users see the TODOs, it does not feel good.

Links:

• Initial PR: f2bb4a8#diff-27fe28b51ff18339baefeed38d4aca5712e10ce0b51bf8db459677f2f0a7f5dfR14-R18
• webpack runtime: https://github.com/webpack/webpack/blob/c586c7b1e027e1d252d68b4372f08a9bce40d96c/lib/hmr/HotModuleReplacement.runtime.js#L30-L32

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[chenjiahan]

I will fix the snapshot tomorrow..