Implement DeclarationMirror.location for all but ParameterMirrors.

tests/lib/mirrors/class_mirror_location_other.dart

 // Copyright (c) 2015, 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.
 
-library enum_duplicate_lib;
+part of test.class_location;
 
-enum Enum1 {
-  A,
-  B,
-}
+class ClassInOtherFile {}
 
-class Enum2 {
-  static Iterable get values => ['Enum2.A', 'Enum2.B'];
-}
+  class SpaceIndentedInOtherFile {}
+
+        class TabIndentedInOtherFile {}