Add length checks to ApiMessageWriter.

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 35 matching lines @@
 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;
     char* as_bigint;
     struct {
-      int length;
+      intptr_t length;
       struct _Dart_CObject** values;
     } as_array;
     struct {
       Dart_TypedData_Type type;
-      int length;
+      intptr_t length;
       uint8_t* values;
     } as_typed_data;
     struct {
       Dart_TypedData_Type type;
-      int length;
+      intptr_t length;
       uint8_t* data;
       void* peer;
       Dart_WeakPersistentHandleFinalizer callback;
     } as_external_typed_data;
   } value;
 } Dart_CObject;
 
 /**
  * Posts a message on some port. The message will contain the
  * Dart_CObject object graph rooted in 'message'.
@@ skipping 107 matching lines @@
  */
 DART_EXPORT Dart_Handle Dart_CompileAll();
 
 /**
  * Check that all function fingerprints are OK.
  *
  */
 DART_EXPORT Dart_Handle Dart_CheckFunctionFingerprints();
 
 #endif  /* INCLUDE_DART_NATIVE_API_H_ */  /* NOLINT */