[ChromeDriver] W3C compliant New Session response

Updating capabilities returned from New Session command for W3C spec
compliance. Change verified by Web Platform Tests (13 additional
new_session tests passed).

Bug: chromedriver:1997
Change-Id: I7683acb33cbf2739a867787ba2a3fedd28be32c5
Reviewed-on: https://chromium-review.googlesource.com/c/1347065
Commit-Queue: John Chen <johnchen@chromium.org>
Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610223}
1 file changed