- Remove entirely disconnected unhandled exception handler.

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
===================================================================
--- runtime/vm/isolate.h	(revision 42724)
+++ runtime/vm/isolate.h	(working copy)
@@ -834,7 +834,6 @@
   char* library_url() const { return library_url_; }
   char* class_name() const { return class_name_; }
   char* function_name() const { return function_name_; }
-  char* exception_callback_name() const { return exception_callback_name_; }
   bool is_spawn_uri() const { return library_url_ == NULL; }
   bool paused() const { return paused_; }
 
@@ -851,7 +850,6 @@
   char* library_url_;
   char* class_name_;
   char* function_name_;
-  char* exception_callback_name_;
   uint8_t* serialized_args_;
   intptr_t serialized_args_len_;
   uint8_t* serialized_message_;