Predicates on Number imply number type.

[mirek]

Fixes #

[typescript-bot]

It looks like you've sent a pull request to update our 'lib' files. These files aren't meant to be edited by hand, as they consist of last-known good states of the compiler and are generated from 'src/lib' or possibly our lib generator. Unless this is necessary, consider closing the pull request and sending a separate PR to update 'src/lib' or https://github.com/microsoft/TypeScript-DOM-lib-generator

[typescript-bot]

This PR doesn't have any linked issues. Please open an issue that references this PR. From there we can discuss and prioritise.

[fatcerberus]

See #39090 (comment). This change is not sound and would require #15048 as a prerequisite.

[sandersn]

@mirek Can you open an issue to design this fix instead? @fatcerberus 's comment does make it sound like it's not possible without some new features in the compiler, though.
In the meantime, to help with PR housekeeping, I'm going to close this PR since the eventual solution will probably be quite a bit larger.