Remove leftover from CL 23038010.

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 367 matching lines @@
   _LocalClosureMirrorImpl(reflectee) : super(reflectee);
 
   MethodMirror _function;
   MethodMirror get function {
     if (_function == null) {
       _function = _computeFunction(reflectee);
     }
     return _function;
   }
 
-  String get source {
-    throw new UnimplementedError(
-        'ClosureMirror.source is not implemented');
-  }
-
   InstanceMirror apply(List<Object> positionalArguments,
                        [Map<Symbol, Object> namedArguments]) {
     // TODO(iposva): When closures get an ordinary call method, this can be
     // replaced with
     //   return this.invoke(#call, positionalArguments, namedArguments);
     // and the native ClosureMirror_apply can be removed.
     
     int numPositionalArguments = positionalArguments.length + 1;  // Receiver.
     int numNamedArguments = namedArguments != null ? namedArguments.length : 0;
     int numArguments = numPositionalArguments + numNamedArguments;
@@ skipping 983 matching lines @@
     if (typeMirror == null) {
       typeMirror = makeLocalTypeMirror(key);
       _instanitationCache[key] = typeMirror;
       if (typeMirror is ClassMirror && !typeMirror._isGeneric) {
         _declarationCache[key] = typeMirror;
       }
     }
     return typeMirror;
   }
 }