Editorial: Align with Web IDL specification

🤖 This is an automated pull request to align the spec with the latest Web IDL specification. 🤖

The followings are the Web IDL validation messages, which may help understanding this PR:

Validation error at line 5 in payment-handler,1:
          Promise<void> enableDelegations(sequence
                  ^

Error: void is now replaced by undefined. Refer to the relevant GitHub issue for more information.

Validation error at line 7 in payment-handler,3:
          Promise<void> set(DOMString
                  ^

Error: void is now replaced by undefined. Refer to the relevant GitHub issue for more information.

Validation error at line 8 in payment-handler,3:
          Promise<void> clear()
                  ^

Error: void is now replaced by undefined. Refer to the relevant GitHub issue for more information.

Validation error at line 7 in payment-handler,7:
          void respondWith(Promise<
          ^

Error: void is now replaced by undefined. Refer to the relevant GitHub issue for more information.

Validation error at line 18 in payment-handler,11:
        void respondWith(Promise<
        ^

Error: void is now replaced by undefined. Refer to the relevant GitHub issue for more information.

Currently this autofix might introduce awkward code formatting, and feel free to manually fix it whenever it happens.

Please file an issue at https://github.com/saschanaz/webidl-updater/issues/new if you think this is invalid or should be enhanced.

w3c / payment-handler