Fixing clang-tidy warning.

Bug: v8:8015
Change-Id: I41b3d7c41ee9f8ff12f70feddcf38f2c9efc5049
Reviewed-on: https://chromium-review.googlesource.com/1224056Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Florian Sattler <sattlerf@google.com>
Cr-Commit-Position: refs/heads/master@{#55917}