Don't use IsolateData for the exit hook as multiple embedders share the dart/bin while using differ…

runtime/bin/isolate_data.h

Index: runtime/bin/isolate_data.h
diff --git a/runtime/bin/isolate_data.h b/runtime/bin/isolate_data.h
index fe76e51d89f530e795b900e03fc6e1c60548d0a3..5ed1ed864f6398bfeb4ff04474587a72205e1841 100644
--- a/runtime/bin/isolate_data.h
+++ b/runtime/bin/isolate_data.h
@@ -16,8 +16,6 @@ namespace bin {
 class EventHandler;
 class Loader;
 
-typedef void (*ExitHook)(int64_t exit_code);
-
 // Data associated with every isolate in the standalone VM
 // embedding. This is used to free external resources for each isolate
 // when the isolate shuts down.
@@ -31,8 +29,7 @@ class IsolateData {
         packages_file(NULL),
         udp_receive_buffer(NULL),
         builtin_lib_(NULL),
-        loader_(NULL),
-        exit_hook_(NULL) {
+        loader_(NULL) {
     if (package_root != NULL) {
       ASSERT(packages_file == NULL);
       this->package_root = strdup(package_root);
@@ -67,9 +64,6 @@ class IsolateData {
     builtin_lib_ = Dart_NewPersistentHandle(lib);
   }
 
-  ExitHook exit_hook() const { return exit_hook_; }
-  void set_exit_hook(ExitHook hook) { exit_hook_ = hook; }
-
   char* script_url;
   char* package_root;
   char* packages_file;
@@ -89,7 +83,6 @@ class IsolateData {
  private:
   Dart_Handle builtin_lib_;
   Loader* loader_;
-  ExitHook exit_hook_;
 
   DISALLOW_COPY_AND_ASSIGN(IsolateData);
 };