V4: remove more superfluous spills.

Spills for targets of phi-nodes are already inserted by the renumbering,
so they don't need to be added (again) while resolving edges.

This fixes a problem with crypto.js.

Change-Id: I4b1d79fc92236b4a6b0b6d6d30ada17c8581a093
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>