XDK heap profiler collector

This is a V8 part of the XDK heap profiler patch
it's a compensation for the new member:
const List<HeapEntry>* entries_;
We need it because originally HeapEntry::index() was implemented as visit to the snapshot and getting of the address of List<HeapEntry> . Since we don't need snapshot (and we don't have it really) we have to provide the pointer to the container  additionally.
It's exactly 4 or 8 more bytes for ia32/em64t