Port r10673 (18d3af5).

Original commit message:
Supports growing non-COW JSArray by a single element if the backing store has room, and initial allocation of a backing store for the store to index zero of an empty array  to kPreallocatedArrayElements elements (e.g. the [] array literal).

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/9378005
Patch from Daniel Kalmar <kalmard@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10707 ce2b1a6d-e550-0410-aec6-3dcde31c8c00