Implement Object.getOwnPropertyDescriptor for element indices and strings (issue 599).

Fix bug for windows 64 bit C calls from generated code.

Add new scons flag unalignedaccesses for arm builds.

Performance improvements on all platforms.


git-svn-id: http://v8.googlecode.com/svn/trunk@4756 ce2b1a6d-e550-0410-aec6-3dcde31c8c00