go/parser: remove superfluous case from switch statement

Change-Id: I96a9b34bf8e42c21a3e0258cbc8b1416328834be
GitHub-Last-Rev: 32709619a690459dc29a32f12cfbd3908ce270e3
GitHub-Pull-Request: golang/go#35066
Reviewed-on: https://go-review.googlesource.com/c/go/+/202598
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

src/go/parser/parser.go

@@ -1446,7 +1446,6 @@ func (p *parser) checkExprOrType(x ast.Expr) ast.Expr {
 	switch t := unparen(x).(type) {
 	case *ast.ParenExpr:
 		panic("unreachable")
-	case *ast.UnaryExpr:
 	case *ast.ArrayType:
 		if len, isEllipsis := t.Len.(*ast.Ellipsis); isEllipsis {
 			p.error(len.Pos(), "expected array length, found '...'")