DEPS.xwalk: Re-roll ozone-wayland to 55f39c6.

When we moved to Chromium 35.0.1916.114 (83d22586), we accidentally
reverted ozone-wayland back to f4faec5, thus losing the fix to
XWALK-1673.
Merge pull request #1997 from rakuco/re-roll-oz-wl

DEPS.xwalk: Re-roll ozone-wayland to 55f39c6.