Remove unused PbMap optional argument

Author: osa1

protobuf/CHANGELOG.md

@@ -7,6 +7,8 @@
   ([#624], [#626])
 * `GeneratedMessage.getField` now initializes map fields. This behavior is
   consistent with `getField` called on repeated fields. ([#373], [#707])
+* Unused and optional `PbMap` constructor argument (`BuilderInfo? info`)
+  removed.
 
 [#183]: https://github.com/google/protobuf.dart/issues/183
 [#644]: https://github.com/google/protobuf.dart/pull/644

protobuf/lib/src/protobuf/pb_map.dart

@@ -24,8 +24,7 @@ class PbMap<K, V> extends MapBase<K, V> {
 
   bool _isReadonly = false;
 
-  // The provided [info] will be ignored.
-  PbMap(this.keyFieldType, this.valueFieldType, [BuilderInfo? info])
+  PbMap(this.keyFieldType, this.valueFieldType)
       : _wrappedMap = <K, V>{};
 
   PbMap.unmodifiable(PbMap other)