This change makes the code compatible with both Python 2 and Python 3.

Change-Id: I99d68af9c3163607c3a2fdbafac339a98b7471e4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1751331
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63207}