Bump crosswalk to Chromium 34.0.1809.0

- Updated DEPS.xwalk to remove custom checkouts
(upstream is already after these revisions)
- Updated gyp files to reflect upstream changes
- Fixed various namespacing issues due to upstream changes
- Fixed various changes in the V8 API (most of the time passing
isolate when required)
- Fixed few new functions in the public interface of content
that are required to reimplement.