DEPS.xwalk: Roll chromium-crosswalk (cb7bc58 -> ddec722)

ddec722 Merge pull request #137 from halton/master
bfcca58 [Backport] Remove X11 and GTK dependencies from host_forwarder
Merge pull request #1751 from rakuco/cr-bump

DEPS.xwalk: Roll chromium-crosswalk (cb7bc58 -> ddec722)