When emerging =dev-lang/v8-9999 the patch v8-gentoo-bug-349794-r0.patch failes to apply. Without this patch everything works fine. I suggest it is because this bug landed upstream http://code.google.com/p/v8/source/detail?r=6463
Created attachment 261085 [details] modified ebuild to not include the failing patch
*** This bug has been marked as a duplicate of bug 352899 ***
Created attachment 261086 [details] build.log
Created attachment 261087 [details] output from failed patch