Turned on with '--log-producers' flag, also needs '--noinline-new' (this is temporarily), '--log-code', '--log-gc'. Not all allocations are traced (I'm investigating.)

Stacks are stored using weak handles. Thus, when an object is collected, its allocation stack is deleted.

Review URL: http://codereview.chromium.org/267077

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3069 ce2b1a6d-e550-0410-aec6-3dcde31c8c00