Revert "cmd/compile: properly handle map assignments for OAS2DOTTYPE"

This reverts commit 9d7c9b4.

For #15602.

Change-Id: I464184b05babe4cb8dedab6161efa730cea6ee2d
Reviewed-on: https://go-review.googlesource.com/22930
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/gc/order.go

@@ -569,24 +569,18 @@ func orderstmt(n *Node, order *Order) {
 
 		orderexprlist(n.List, order)
 		n.Rlist.First().Left = orderexpr(n.Rlist.First().Left, order, nil) // i in i.(T)
-
-		results := n.List.Slice()
-		var assigns [2]*Node
-
-		for r, res := range results {
-			if !isblank(res) {
-				results[r] = ordertemp(res.Type, order, haspointers(res.Type))
-				assigns[r] = Nod(OAS, res, results[r])
-			}
+		if isblank(n.List.First()) {
+			order.out = append(order.out, n)
+		} else {
+			typ := n.Rlist.First().Type
+			tmp1 := ordertemp(typ, order, haspointers(typ))
+			order.out = append(order.out, n)
+			r := Nod(OAS, n.List.First(), tmp1)
+			r = typecheck(r, Etop)
+			ordermapassign(r, order)
+			n.List.Set([]*Node{tmp1, n.List.Second()})
 		}
-		order.out = append(order.out, n)
 
-		for _, assign := range assigns {
-			if assign != nil {
-				assign = typecheck(assign, Etop)
-				ordermapassign(assign, order)
-			}
-		}
 		cleantemp(t, order)
 
 		// Special: use temporary variables to hold result,