stream: fixed misplaced comment
Checklist
-
make -j8 test
(UNIX), orvcbuild test nosign
(Windows) passes -
commit message follows commit guidelines
Affected core subsystem(s)
stream
Description of change
In e26622bd, a comment was incorrectly moved from the code it was describing. The comment has been moved back to its original location.. Fixes: https://github.com/nodejs/node/issues/8856