It's unused.

BUG=v8:5717

Change-Id: I2609d8fd686e74ab31ea2f21d247d054305b2cad
Reviewed-on: https://chromium-review.googlesource.com/451357
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43634}