Support isExternal method on MethodMirror in the Dart VM. Not really intended for public consumptio…

runtime/lib/mirrors.h

 // Copyright (c) 2011, 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.
 
 #ifndef LIB_MIRRORS_H_
 #define LIB_MIRRORS_H_
 
 #include "vm/allocation.h"
 
 namespace dart {
 
 class Mirrors : public AllStatic {
  public:
   #define MIRRORS_KIND_SHIFT_LIST(V)                                           \
     V(kAbstract)                                                               \
     V(kGetter)                                                                 \
     V(kSetter)                                                                 \
     V(kConstructor)                                                            \
     V(kConstCtor)                                                              \
     V(kGenerativeCtor)                                                         \
     V(kRedirectingCtor)                                                        \
     V(kFactoryCtor)                                                            \
+    V(kExternal)                                                               \
 
   // These offsets much be kept in sync with those in mirrors_impl.dart.
   enum KindShifts {
   #define DEFINE_KIND_SHIFT_ENUM(name) name,
   MIRRORS_KIND_SHIFT_LIST(DEFINE_KIND_SHIFT_ENUM)
   #undef DEFINE_KIND_SHIFT_ENUM
   };
 };
 
 }  // namespace dart
 
 #endif  // LIB_MIRRORS_H_