Do not overwrite event logger when we explicitly have --log-timer-events.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index ab1364715bd67bf7e6bf770d349ead945b96d079..bfd10110a01e32bae663311ccad937909d7cf8cc 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -6649,6 +6649,8 @@ void Isolate::GetHeapStatistics(HeapStatistics* heap_statistics) {
 
 
 void Isolate::SetEventLogger(LogEventCallback that) {
+  // Do not overwrite the event logger if we want to log explicitly.
+  if (i::FLAG_log_timer_events) return;
   i::Isolate* isolate = reinterpret_cast<i::Isolate*>(this);
   isolate->set_event_logger(that);
 }