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

runtime/bin/io_buffer.cc

Index: runtime/bin/io_buffer.cc
diff --git a/runtime/bin/io_buffer.cc b/runtime/bin/io_buffer.cc
index 8ff95a05e27e146744cc6f6a9ce5d9b1f049691c..a07559d853483a83553868fc07882bebc58f54cc 100644
--- a/runtime/bin/io_buffer.cc
+++ b/runtime/bin/io_buffer.cc
@@ -4,19 +4,11 @@
 
 #include "bin/io_buffer.h"
 
-static void BufferFree(void* buffer) {
-  delete[] reinterpret_cast<uint8_t*>(buffer);
-}
-
-
 Dart_Handle IOBuffer::Allocate(intptr_t size, uint8_t **buffer) {
-  uint8_t* data = new uint8_t[size];
-  Dart_Handle result = Dart_NewExternalByteArray(data,
-                                                 size,
-                                                 data,
-                                                 BufferFree);
+  uint8_t* data = Allocate(size);
+  Dart_Handle result = Dart_NewExternalByteArray(data, size, data, Free);
   if (Dart_IsError(result)) {
-    BufferFree(data);
+    Free(data);
     Dart_PropagateError(result);
   }
   if (buffer != NULL) {
@@ -24,3 +16,7 @@ Dart_Handle IOBuffer::Allocate(intptr_t size, uint8_t **buffer) {
   }
   return result;
 }
+
+uint8_t* IOBuffer::Allocate(intptr_t size) {
+  return new uint8_t[size];
+}