ChromeDriver v2 and WebDriverJS API upgrade, desktop Chrome works.

The included chromedriver binary fails the initial screenshot (on a blank page with a data: URL), which does not fail the test, but just has no start white frame for WebDriver tests (non-WD tests are unaffected). This is fixed in chromedriver v2.4, which ships next week. I verified it on my local build from head on a Mac, but I'll do another commit with the proper released binaries for all 3 platforms.