encoding/protojson, encoding/prototext: remove most explicit registries

Change tests which use private types registries to use the global one.
Except in cases where we want to explicitly test that the private
registry is used, it's simpler to use the global registry.

Change-Id: I998fb463b6beef91c7f5ce2ca2083251ae24d1db
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/199897
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
Reviewed-by: Herbie Ong <herbie@google.com>
diff --git a/encoding/prototext/encode_test.go b/encoding/prototext/encode_test.go
index 68ceb45..ec5a225 100644
--- a/encoding/prototext/encode_test.go
+++ b/encoding/prototext/encode_test.go
@@ -13,7 +13,6 @@
 	"google.golang.org/protobuf/internal/detrand"
 	"google.golang.org/protobuf/internal/encoding/pack"
 	"google.golang.org/protobuf/internal/flags"
-	pimpl "google.golang.org/protobuf/internal/impl"
 	"google.golang.org/protobuf/proto"
 	preg "google.golang.org/protobuf/reflect/protoregistry"
 
@@ -1130,7 +1129,7 @@
 	}, {
 		desc: "Any not expanded",
 		mo: prototext.MarshalOptions{
-			Resolver: preg.NewTypes(),
+			Resolver: new(preg.Types),
 		},
 		input: func() proto.Message {
 			m := &pb2.Nested{
@@ -1153,9 +1152,6 @@
 `,
 	}, {
 		desc: "Any expanded",
-		mo: prototext.MarshalOptions{
-			Resolver: preg.NewTypes(pimpl.Export{}.MessageTypeOf(&pb2.Nested{})),
-		},
 		input: func() proto.Message {
 			m := &pb2.Nested{
 				OptString: proto.String("embedded inside Any"),
@@ -1181,9 +1177,6 @@
 `,
 	}, {
 		desc: "Any expanded with missing required",
-		mo: prototext.MarshalOptions{
-			Resolver: preg.NewTypes(pimpl.Export{}.MessageTypeOf(&pb2.PartialRequired{})),
-		},
 		input: func() proto.Message {
 			m := &pb2.PartialRequired{
 				OptString: proto.String("embedded inside Any"),
@@ -1206,9 +1199,6 @@
 `,
 	}, {
 		desc: "Any with invalid value",
-		mo: prototext.MarshalOptions{
-			Resolver: preg.NewTypes(pimpl.Export{}.MessageTypeOf(&pb2.Nested{})),
-		},
 		input: &anypb.Any{
 			TypeUrl: "foo/pb2.Nested",
 			Value:   []byte("\x80"),