[ChromeDriver] Add Cookie spec compliance

Make Add Cookie command compliant to W3C spec. Also added a set of
helper functions to help parsing some property types used in W3C spec.
ChromeDriver now passes all WPT WebDriver tests related to cookie.

Bug: chromedriver:2002
Change-Id: I3779a14e010bca865498a9d40710974e38ede829
Reviewed-on: https://chromium-review.googlesource.com/c/1366925
Commit-Queue: John Chen <johnchen@chromium.org>
Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615539}
6 files changed