Version 3.28.48 (based on bleeding_edge revision r22686)

Fix Object.freeze with field type tracking. Keep the descriptor properly intact while update the field type (issue 3458).

Performance and stability improvements on all platforms.

git-svn-id: https://v8.googlecode.com/svn/trunk@22688 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/trunk' into trunk