[dev.go2go] cmd/compile/internal/syntax: accept [] for type parameter…

… lists

Still missing:
- embedded []-instantiated types in interfaces
- *B.go2 tests which exist for go/types

Change-Id: I3dd115fcd67f725144062c90550a91fcded1cbe2
Reviewed-on: https://go-review.googlesource.com/c/go/+/246259
Reviewed-by: Robert Griesemer <gri@golang.org>

src/cmd/compile/internal/syntax/nodes.go

@@ -225,9 +225,10 @@ type (
 
 	// Fun(ArgList[0], ArgList[1], ...)
 	CallExpr struct {
-		Fun     Expr
-		ArgList []Expr // nil means no arguments
-		HasDots bool   // last argument is followed by ...
+		Fun      Expr
+		ArgList  []Expr // nil means no arguments
+		HasDots  bool   // last argument is followed by ...
+		Brackets bool   // []'s instead of ()'s
 		expr
 	}