Add typed data interface to Dart API, this only changes the C++ API as dicussed in a previous email…

bin/io_buffer.cc

Index: bin/io_buffer.cc
===================================================================
--- bin/io_buffer.cc	(revision 18484)
+++ bin/io_buffer.cc	(working copy)
@@ -6,7 +6,8 @@
 
 Dart_Handle IOBuffer::Allocate(intptr_t size, uint8_t **buffer) {
   uint8_t* data = Allocate(size);
-  Dart_Handle result = Dart_NewExternalByteArray(data, size,
+  Dart_Handle result = Dart_NewExternalTypedData(data,
+                                                 kUint8, size,
                                                  data, IOBuffer::Finalizer);
   if (Dart_IsError(result)) {
     Free(data);