Implement MethodMirror.location in the VM.

tests/lib/mirrors/mirrors_reader_test.dart

 // Copyright (c) 2014, 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.
 
 // Test that everything reachable from a [MirrorSystem] can be accessed.
 
 library test.mirrors.reader;
 
 import 'dart:mirrors';
 import 'mirrors_reader.dart';
@@ skipping 14 matching lines @@
       if (tag.endsWith('.metadata')) {
         return true;// Issue 10905.
       }
     }
     return false;
   }
 
   bool expectUnsupported(var receiver, String tag, UnsupportedError exception) {
     // [DeclarationMirror.location] is intentionally not supported in runtime
     // mirrors.
-    if (receiver is DeclarationMirror && tag == 'location') {
-      return true;
-    }
+
     if (mirrorSystemType == '_LocalMirrorSystem') {
       // VM mirror system.
+      if (receiver is DeclarationMirror && tag == 'location') {
+        return receiver is! MethodMirror;
+      }
     } else if (mirrorSystemType == 'JsMirrorSystem') {
       // Dart2js runtime mirror system.
+      if (receiver is DeclarationMirror && tag == 'location') {
+        return true;
+      }
     }
     return false;
   }
 }
 
 void main([List<String> arguments = const <String>[]]) {
   MirrorSystem mirrors = currentMirrorSystem();
   MirrorsReader reader = new RuntimeMirrorsReader(mirrors,
       verbose: arguments.contains('-v'),
       includeStackTrace: arguments.contains('-s'));
   reader.checkMirrorSystem(mirrors);
 }