V4: Fix SSA decomposition when no regalloc is used.

Add scheduling for moves generated by removing phi nodes by re-using the
MoveMapping class from the register allocator. This change applies to
both the JIT when no register allocator is used, and the interpreter.

Change-Id: I38eac5b13759c7790132d1ef07fa17fcb53187e3
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>