Implement ParameterMirror.metadata.

runtime/lib/mirrors_impl.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // VM-specific implementation of the dart:mirrors library.
 
 import "dart:collection";
 
 // These values are allowed to be passed directly over the wire.
 bool _isSimpleValue(var value) {
@@ skipping 1144 matching lines @@
 
 class _LocalParameterMirrorImpl extends _LocalVariableMirrorImpl
     implements ParameterMirror {
   _LocalParameterMirrorImpl(reflectee,
                             String simpleName,
                             DeclarationMirror owner,
                             this._position,
                             this.isOptional,
                             this.isNamed,
                             bool isFinal,
-                            this._defaultValueReflectee)
+                            this._defaultValueReflectee,
+                            this._unmirroredMetadata)
       : super(reflectee,
               simpleName,
               owner,
               null,  // We override the type.
               false, // isStatic does not apply.
               isFinal);
 
   final int _position;
   final bool isOptional;
   final bool isNamed;
+  final List _unmirroredMetadata;
 
   Object _defaultValueReflectee;
   InstanceMirror _defaultValue;
   InstanceMirror get defaultValue {
     if (!isOptional) {
       return null;
     }
     if (_defaultValue == null) {
       _defaultValue = reflect(_defaultValueReflectee);
     }
     return _defaultValue;
   }
 
   bool get hasDefaultValue => _defaultValueReflectee != null;
 
-  // TODO(11418): Implement.
   List<InstanceMirror> get metadata {
-    throw new UnimplementedError(
-        'ParameterMirror.metadata is not implemented');
+    if ( _unmirroredMetadata == null) return const [];
+    return _unmirroredMetadata.map(reflect).toList(growable:false);
   }
 
   TypeMirror _type = null;
   TypeMirror get type {
     if (_type == null) {
       _type =
           _Mirrors._reflectType(_ParameterMirror_type(_reflectee, _position));
     }
     return _type;
   }
@@ skipping 103 matching lines @@
     if (typeMirror == null) {
       typeMirror = makeLocalTypeMirror(key);
       _instanitationCache[key] = typeMirror;
       if (typeMirror is ClassMirror && !typeMirror._isGeneric) {
         _declarationCache[key] = typeMirror;
       }
     }
     return typeMirror;
   }
 }