[ChromeDriver] Chromedriver 2.38 release

Change-Id: I4d720df1d47dd095a0cbfc65b774fedce244911d
Reviewed-on: https://chromium-review.googlesource.com/1015085Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Artur Khachatryan <khachatryan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551455}

chrome/test/chromedriver/VERSION

-2.37
+2.38