Minor refactoring, for readability and performance.

R=ahaas@chromium.org

Bug: v8:8015
Change-Id: I30c4a76998c8867aea0e08fd982b4425d4ae8fef
Reviewed-on: https://chromium-review.googlesource.com/1251163Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56285}