Revert previous change: complexN only converts to complexN.
Revert previous change: complexN only converts to complexN.

This was discussed with Ken and Russ.  6g has been changed,
and both compilers now work this way.  This avoids a double
type conversion--first to the float type, then to the complex
type.

R=r
CC=golang-dev, ken2, rsc
http://codereview.appspot.com/419042

rdp/rogerpack2005-golang,d0f/go-zh,bryanxu/go-zh,webfd/go-zh,bryanxu/go-zh,scirelli/scirelli-go,webfd/go-zh,mhennings/marcohennings-go,rdp/rogerpack2005-golang,scirelli/scirelli-go,rflanagan/reginaldflanagan-project1,webfd/go-zh,rflanagan/reginaldflanagan-project1,Triskite/willstone-goclone,webfd/go-zh,scirelli/scirelli-go,Triskite/willstone-goclone,sanjosh/sanjos100-tipc,d0f/go-zh,rdp/rogerpack2005-golang,sanjosh/sanjos100-tipc,scirelli/scirelli-go,glycerine/jeaten-go-arrayof-structof,scirelli/scirelli-go,glycerine/jeaten-go-arrayof-structof,npe9/noahevans-go9,bryanxu/go-zh,sanjosh/sanjos100-tipc,rdp/rogerpack2005-golang,npe9/noahevans-go9,rdp/rogerpack2005-golang,npe9/noahevans-go9,scirelli/scirelli-go,bryanxu/go-zh,mhennings/marcohennings-go,glycerine/jeaten-go-arrayof-structof,rdp/rogerpack2005-golang,d0f/go-zh,rdp/rogerpack2005-golang,webfd/go-zh,Triskite/willstone-goclone,sanjosh/sanjos100-tipc,bryanxu/go-zh,Triskite/willstone-goclone,webfd/go-zh,scirelli/scirelli-go,npe9/noahevans-go9,glycerine/jeaten-go-arrayof-structof,rflanagan/reginaldflanagan-project1,glycerine/jeaten-go-arrayof-structof,sanjosh/sanjos100-tipc,mhennings/marcohennings-go,Triskite/willstone-goclone,rflanagan/reginaldflanagan-project1,bryanxu/go-zh,sanjosh/sanjos100-tipc,Triskite/willstone-goclone,d0f/go-zh,sanjosh/sanjos100-tipc,sanjosh/sanjos100-tipc,mhennings/marcohennings-go,mhennings/marcohennings-go,rflanagan/reginaldflanagan-project1,npe9/noahevans-go9,mhennings/marcohennings-go,d0f/go-zh,rflanagan/reginaldflanagan-project1,glycerine/jeaten-go-arrayof-structof,Triskite/willstone-goclone,rdp/rogerpack2005-golang,webfd/go-zh,scirelli/scirelli-go,d0f/go-zh,npe9/noahevans-go9,bryanxu/go-zh,mhennings/marcohennings-go,glycerine/jeaten-go-arrayof-structof,rflanagan/reginaldflanagan-project1,glycerine/jeaten-go-arrayof-structof,npe9/noahevans-go9,Triskite/willstone-goclone,d0f/go-zh,npe9/noahevans-go9,d0f/go-zh,mhennings/marcohennings-go,rflanagan/reginaldflanagan-project1,webfd/go-zh,bryanxu/go-zh