Start 'fuzzing' of dart:io APIs and fix first issue found.

runtime/include/dart_api.h

 // Copyright (c) 2012, 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_API_H_
 #define INCLUDE_DART_API_H_
 
 /** \mainpage Dart Embedding API Reference
  *
  * Dart is a class-based programming language for creating structured
@@ skipping 675 matching lines @@
   enum Type {
     kNull = 0,
     kBool,
     kInt32,
     kInt64,
     kBigint,
     kDouble,
     kString,
     kArray,
     kUint8Array,
+    kUnsupported,
     kNumberOfTypes
   };
   Type type;
   union {
     bool as_bool;
     int32_t as_int32;
     int64_t as_int64;
     double as_double;
     char* as_string;
     char* as_bigint;
@@ skipping 1316 matching lines @@
 
 // --- Profiling support ----
 
 // External pprof support for gathering and dumping symbolic
 // information that can be used for better profile reports for
 // dynamically generated code.
 DART_EXPORT void Dart_InitPprofSupport();
 DART_EXPORT void Dart_GetPprofSymbolInfo(void** buffer, int* buffer_size);
 
 #endif  // INCLUDE_DART_API_H_