Move the flakiness dashboard above the results by builder

The flakiness dashboard isn't specific to a given builder, which means it
should be above the information that's builder-specific.

R=ojan@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/398863002

git-svn-id: svn://svn.chromium.org/blink/trunk@178290 bbb929c8-8fbe-4397-9dbb-9b2b20218538