Support sending and receiving Capability objects from C code.

runtime/include/dart_native_api.h

 /*
  * Copyright (c) 2013, 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 INCLUDE_DART_NATIVE_API_H_
 #define INCLUDE_DART_NATIVE_API_H_
 
 #include "include/dart_api.h"
@@ skipping 22 matching lines @@
   Dart_CObject_kBool,
   Dart_CObject_kInt32,
   Dart_CObject_kInt64,
   Dart_CObject_kBigint,
   Dart_CObject_kDouble,
   Dart_CObject_kString,
   Dart_CObject_kArray,
   Dart_CObject_kTypedData,
   Dart_CObject_kExternalTypedData,
   Dart_CObject_kSendPort,
+  Dart_CObject_kCapability,
   Dart_CObject_kUnsupported,
   Dart_CObject_kNumberOfTypes
 } Dart_CObject_Type;
 
 typedef struct _Dart_CObject {
   Dart_CObject_Type type;
   union {
     bool as_bool;
     int32_t as_int32;
     int64_t as_int64;
     double as_double;
     char* as_string;
     struct {
       bool neg;
       intptr_t used;
       struct _Dart_CObject* digits;
     } as_bigint;
     struct {
       Dart_Port id;
       Dart_Port origin_id;
     } as_send_port;
     struct {
+      int64_t id;
+    } as_capability;
+    struct {
       intptr_t length;
       struct _Dart_CObject** values;
     } as_array;
     struct {
       Dart_TypedData_Type type;
       intptr_t length;
       uint8_t* values;
     } as_typed_data;
     struct {
       Dart_TypedData_Type type;
@@ skipping 75 matching lines @@
 
 /**
  * Forces all loaded classes and functions to be compiled eagerly in
  * the current isolate..
  *
  * TODO(turnidge): Document.
  */
 DART_EXPORT Dart_Handle Dart_CompileAll();
 
 #endif  /* INCLUDE_DART_NATIVE_API_H_ */  /* NOLINT */