Implement ParameterMirror.{isFinal,hasDefaultValue,defaultValue}.

runtime/lib/mirrors_impl.dart

Index: runtime/lib/mirrors_impl.dart
diff --git a/runtime/lib/mirrors_impl.dart b/runtime/lib/mirrors_impl.dart
index ea63f9079e4d381b0ac2b2965447296bc1a3cce4..19c8520665b4359eea5f6100fcd12bd74808ebad 100644
--- a/runtime/lib/mirrors_impl.dart
+++ b/runtime/lib/mirrors_impl.dart
@@ -1077,27 +1077,30 @@ class _LocalParameterMirrorImpl extends _LocalVariableMirrorImpl
                             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 (_defaultValue == null && isOptional) {
+      _defaultValue = reflect(_defaultValueReflectee);
+    }

[siva, 2013/08/26 05:05:43]

Maybe write as:

if (!isOptional) {
  return false;
}
if (_defaultValue == null) {
  _defaultValue = reflect(_defaultValueReflectee);
}
return _defaultValue;

[Michael Lippautz (Google), 2013/08/26 19:45:57]

Rewrote using this pattern, with the difference that it returns null in the case
that this is not an optional parameter. (Conform to the spec.)

+    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 {