reflect/protoreflect: rename methods with Type suffix

The protobuf type system uses the word "descriptor" instead of "type".
We should avoid the "type" verbage when we aren't talking about Go types.
The old names are temporarily kept around for compatibility reasons.

Change-Id: Icc99c913528ead011f7a74aa8399d9c5ec6dc56e
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/172238
Reviewed-by: Herbie Ong <herbie@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/internal/impl/legacy_test.go b/internal/impl/legacy_test.go
index 84cf071..799289b 100644
--- a/internal/impl/legacy_test.go
+++ b/internal/impl/legacy_test.go
@@ -769,7 +769,7 @@
 								// Ignore New since it a constructor.
 							case "Options":
 								// Ignore descriptor options since protos are not cmperable.
-							case "EnumType", "MessageType", "ExtendedType":
+							case "Oneof", "Extendee", "Enum", "Message":
 								// Avoid descending into a dependency to avoid a cycle.
 								// Just record the full name if available.
 								//
@@ -778,6 +778,12 @@
 								if !v.IsNil() {
 									out[name] = v.Interface().(pref.Descriptor).FullName()
 								}
+							// TODO: Remove this when the methods are deleted.
+							case "OneofType", "ExtendedType", "EnumType", "MessageType":
+								v := m.Call(nil)[0]
+								if !v.IsNil() {
+									out[name] = v.Interface().(pref.Descriptor).FullName()
+								}
 							default:
 								out[name] = m.Call(nil)[0].Interface()
 							}