{std::ostream} was used without including either <ostream> or <iosfwd>.

R=ahaas@chromium.org

Change-Id: I92facf672c81a17e2ff24658bbefd961b4f4d445
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2248196Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68385}