[Interpreter] Do not write Ignition dispatch counters to file by default.

src/d8.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 
 // Defined when linking against shared lib on Windows.
 #if defined(USING_V8_SHARED) && !defined(V8_SHARED)
 #define V8_SHARED
 #endif
 
@@ skipping 2477 matching lines @@
       result = RunMain(isolate, argc, argv, last_run);
     }
 
     // Run interactive shell if explicitly requested or if no script has been
     // executed, but never on --test
     if (options.use_interactive_shell()) {
       RunShell(isolate);
     }
 
 #ifndef V8_SHARED
-    if (i::FLAG_ignition && i::FLAG_trace_ignition_dispatches) {
+    if (i::FLAG_ignition && i::FLAG_trace_ignition_dispatches &&
+        i::FLAG_trace_ignition_dispatches_output_file != nullptr) {
       WriteIgnitionDispatchCountersFile(isolate);
     }
 #endif
 
     // Shut down contexts and collect garbage.
     evaluation_context_.Reset();
 #ifndef V8_SHARED
     stringify_function_.Reset();
 #endif  // !V8_SHARED
     CollectGarbage(isolate);
@@ skipping 16 matching lines @@
 }
 
 }  // namespace v8
 
 
 #ifndef GOOGLE3
 int main(int argc, char* argv[]) {
   return v8::Shell::Main(argc, argv);
 }
 #endif