This trick is confusing a bit the heap snapshoting code.
Such a shiffted array will be interpreted as a new array in the second snapshot.

BUG=none
TEST=HeapEntryIdsAndArrayShift

Review URL: https://chromiumcodereview.appspot.com/9748007

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11096 ce2b1a6d-e550-0410-aec6-3dcde31c8c00