* Persist farbling token per schemeful site.
* Add tests for persistent farbling token.
* Handle shields metadata cleanup on site data remove.
* Update existing tests to work with the new farbling random.
* Disable farbling in some sensitive Chromium tests.
* Simplify GetShieldsMetadata.
* Use ASSERT instead of CHECK in tests.
* Alias objects memory in dumps to see the actual types.
* Few improvements to harden the object alias helper.
* Remove StackObjectCopy from this PR (better to land it separately).