[chromedriver] Reenable ParseCapabilities.MobileEmulationDeviceName, since it no longer depends on files generated from Blink sources.

BUG=392430

Review URL: https://codereview.chromium.org/399173003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284004 0039d316-1c4b-4281-b951-d872f2087c98