Introduce JIT code events dispatcher for the isolate.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 3dcf6f5dde40936d542517481e6309a589b820c9..31f51bef93838df80764a60179b1d6a9bb6f7db7 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -1862,6 +1862,7 @@ Isolate::Isolate(bool enable_serializer)
       is_tail_call_elimination_enabled_(true),
       cpu_profiler_(NULL),
       heap_profiler_(NULL),
+      code_event_dispatcher_(new CodeEventDispatcher()),
       function_entry_hook_(NULL),
       deferred_handles_head_(NULL),
       optimizing_compile_dispatcher_(NULL),
@@ -2019,6 +2020,8 @@ void Isolate::Deinit() {
   delete cpu_profiler_;
   cpu_profiler_ = NULL;
 
+  code_event_dispatcher_.reset();
+
   delete root_index_map_;
   root_index_map_ = NULL;