Fix mozilla and debug check failures.

Fix mozilla and debug check failures.

This removes the expected failure of a mozilla test that we now pass
(an empty array is returned if Array.splice is called with no
arguments) and fixes debug check failure by allocating a new empty
array using AllocateEmptyArray if splice is called with zero arguments
(makes sure we can always create a handle).

Review URL: http://codereview.chromium.org/3218010

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5377 ce2b1a6d-e550-0410-aec6-3dcde31c8c00