Also changes occurrences of 'length' with kLengthString.

R=mvstanton@chromium.org

Bug: v8:8015
Change-Id: Ida205a7d69939d7d3473e1ab8e82d0cdba4c8668
Reviewed-on: https://chromium-review.googlesource.com/1209302Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Simon Zünd <szuend@google.com>
Cr-Commit-Position: refs/heads/master@{#55686}