back to T{x}, stricter handling of T(x) vs x.(T)

R=ken
DELTA=131  (60 added, 41 deleted, 30 changed)
OCL=25617
CL=25633
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 0f8d265..8445a91 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -327,9 +327,9 @@
 	ONOT, OCOM, OPLUS, OMINUS, OSEND, ORECV,
 	OLITERAL, OREGISTER, OINDREG,
 	OKEY, OPARAM,
+	OCOMPOS,
 	OCONV,
-	OCONVDOT,
-	OCONVPAREN,
+	ODOTTYPE,
 	OBAD,
 
 	OEXTEND,	// 6g internal