Make all allocation of external arrays used for IO use the IOBuffer class

runtime/bin/dartutils.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 BIN_DARTUTILS_H_
 #define BIN_DARTUTILS_H_
 
 #include "bin/builtin.h"
 #include "bin/utils.h"
 #include "include/dart_api.h"
@@ skipping 213 matching lines @@
   // TODO(sgjesse): Add support for kBigint.
   static Dart_CObject* NewDouble(double value);
   static Dart_CObject* NewString(int length);
   static Dart_CObject* NewString(const char* str);
   static Dart_CObject* NewArray(int length);
   static Dart_CObject* NewUint8Array(int length);
   static Dart_CObject* NewExternalUint8Array(int64_t length,
                                              uint8_t* data,
                                              void* peer,
                                              Dart_PeerFinalizer callback);
+  static Dart_CObject* NewIOBuffer(int64_t length);
+  static void FreeIOBufferData(Dart_CObject* object);
 
   Dart_CObject* AsApiCObject() { return cobject_; }
 
   // Create a new CObject array with an illegal arguments error.
   static CObject* IllegalArgumentError();
   // Create a new CObject array with a file closed error.
   static CObject* FileClosedError();
   // Create a new CObject array with the current OS error.
   static CObject* NewOSError();
   // Create a new CObject array with the specified OS error.
@@ skipping 153 matching lines @@
  private:
   DISALLOW_COPY_AND_ASSIGN(CObjectUint8Array);
 };
 
 
 class CObjectExternalUint8Array : public CObject {
  public:
   DECLARE_COBJECT_CONSTRUCTORS(ExternalUint8Array)
 
   int Length() const { return cobject_->value.as_external_byte_array.length; }
+  void SetLength(uint64_t length) {
+    cobject_->value.as_external_byte_array.length = length;
+  }
   uint8_t* Data() const { return cobject_->value.as_external_byte_array.data; }
   void* Peer() const { return cobject_->value.as_external_byte_array.peer; }
   Dart_PeerFinalizer Callback() const {
     return cobject_->value.as_external_byte_array.callback;
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(CObjectExternalUint8Array);
 };
 
 #endif  // BIN_DARTUTILS_H_