[chromedriver] Release version 2.11

BUG=

Review URL: https://codereview.chromium.org/626233002

Cr-Commit-Position: refs/heads/master@{#298600}
[chromedriver] Change CHROME_38_REVISION from 290109 to 289947

For some reason 290109 doesn't exist in the continuous archive for Windows.

BUG=
NOTRY=true
TBR=stgao@chromium.org

Review URL: https://codereview.chromium.org/638733003

Cr-Commit-Position: refs/heads/master@{#298605}