Fix by removing a method with a single user instead of introducing an
inl-header.

R=mstarzinger@chromium.org

Bug: v8:7965
Change-Id: I596a673f36c63197db3e774d24b65abe01e83399
Reviewed-on: https://chromium-review.googlesource.com/c/1303717
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57071}