Methods defined within a class declaration are always inline by default,
hence remove the redundant annotations.

R=thibaudm@chromium.org

Change-Id: I08e86996bad9596936220da849cdfaec5fffe1f9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2449970Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70368}