[counters] Making counter properly reentrant.

src/vm-state-inl.h

Index: src/vm-state-inl.h
diff --git a/src/vm-state-inl.h b/src/vm-state-inl.h
index d60548d27d131126b0f2c38c34a9a2c8da668104..0bfc47a27576d77ee8ad705cea08702f887f50ab 100644
--- a/src/vm-state-inl.h
+++ b/src/vm-state-inl.h
@@ -54,8 +54,8 @@ VMState<Tag>::~VMState() {
   isolate_->set_current_vm_state(previous_tag_);
 }
 
-
 ExternalCallbackScope::ExternalCallbackScope(Isolate* isolate, Address callback)
+

[Jarin, 2016/02/13 19:28:20]

Nit: Extra newline?

     : isolate_(isolate),
       callback_(callback),
       previous_scope_(isolate->external_callback_scope()) {
@@ -63,9 +63,16 @@ ExternalCallbackScope::ExternalCallbackScope(Isolate* isolate, Address callback)
   scope_address_ = Simulator::current(isolate)->get_sp();
 #endif
   isolate_->set_external_callback_scope(this);
+  if (FLAG_runtime_call_stats) {
+    RuntimeCallStats* stats = isolate_->counters()->runtime_call_stats();
+    stats->Enter(&stats->RuntimeCallbacks);
+  }
 }
 
 ExternalCallbackScope::~ExternalCallbackScope() {
+  if (FLAG_runtime_call_stats) {
+    isolate_->counters()->runtime_call_stats()->Leave();
+  }
   isolate_->set_external_callback_scope(previous_scope_);
 }