Implement ParameterMirror.{isFinal,hasDefaultValue,defaultValue}.

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 1071 matching lines @@
       native "VariableMirror_type";
 }
 
 class _LocalParameterMirrorImpl extends _LocalVariableMirrorImpl
     implements ParameterMirror {
   _LocalParameterMirrorImpl(reflectee,
                             String simpleName,
                             DeclarationMirror owner,
                             this._position,
                             this.isOptional,
-                            this.isNamed)
+                            this.isNamed,
+                            bool isFinal,
+                            this._defaultValueReflectee)
       : super(reflectee,
               simpleName,
               owner,
               null,  // We override the type.
               false, // isStatic does not apply.
-              false);  // TODO(12196): Not yet implemented.
+              isFinal);
 
   final int _position;
   final bool isOptional;
   final bool isNamed;
 
-  String get defaultValue {
-    throw new UnimplementedError(
-        'ParameterMirror.defaultValue is not implemented');
+  Object _defaultValueReflectee;
+  InstanceMirror _defaultValue = null;
+  InstanceMirror get defaultValue {
+    if (!isOptional) {
+      return null;
+    }
+    if (_defaultValue == null) {
+      _defaultValue = reflect(_defaultValueReflectee);
+    }
+    return _defaultValue;
   }
 
-  bool get hasDefaultValue {
-    throw new UnimplementedError(
-        'ParameterMirror.hasDefaultValue is not implemented');
-  }
+  bool get hasDefaultValue => _defaultValueReflectee != null;
 
   // TODO(11418): Implement.
   List<InstanceMirror> get metadata {
     throw new UnimplementedError(
         'ParameterMirror.metadata is not implemented');
   }
 
   TypeMirror _type = null;
   TypeMirror get type {
     if (_type == null) {
@@ skipping 108 matching lines @@
     if (typeMirror == null) {
       typeMirror = makeLocalTypeMirror(key);
       _instanitationCache[key] = typeMirror;
       if (typeMirror is ClassMirror && !typeMirror._isGeneric) {
         _declarationCache[key] = typeMirror;
       }
     }
     return typeMirror;
   }
 }