DEPS.xwalk: Roll chromium-crosswalk (c524f0d -> b93afe0).

* b93afe0 Merge pull request #182 from rakuco/fix-angle-roll
* 7fe3516 [Temp] Fix ANGLE's hash after ab6d5f16.
* 6708f05 Merge pull request #181 from rakuco/roll-angle-deps
* ab6d5f1 [Temp] Roll ANGLE to 5ac2ae3ea1f311be61955b2d554e8510474cf4f0.
* 8dffdb1 Merge pull request #178 from wang16/master
* 13884df [Android] Implement ScreenOrientation.unlock align with spec

This roll includes a change in the ANGLE hash in chromium-crosswalk that
allows us to get rid of the custom patch we were carrying for Tizen.