[ChromeDriver] Allow null value for script timeout

Bug: chromedriver:2796
Change-Id: If8ea3747baac59a7deb6a63c5abb15ca9695abda
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1521768
Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Tatiana Buldina <buldina@chromium.org>
Cr-Commit-Position: refs/heads/master@{#640940}
2 files changed