[turbofan] Fix turbo json file generation for code stubs.

src/compiler/pipeline.cc

Index: src/compiler/pipeline.cc
diff --git a/src/compiler/pipeline.cc b/src/compiler/pipeline.cc
index 5c4dd46a5d727c91d581ab8955342798a73c8e69..7de0a1170e4d144d221c78b4987b1c47f2aab1e9 100644
--- a/src/compiler/pipeline.cc
+++ b/src/compiler/pipeline.cc
@@ -1496,9 +1496,11 @@ Handle<Code> Pipeline::GenerateCodeForCodeStub(Isolate* isolate,
   DCHECK_NOT_NULL(data.schedule());
 
   if (FLAG_trace_turbo) {
-    TurboJsonFile json_of(&info, std::ios_base::trunc);
-    json_of << "{\"function\":\"" << info.GetDebugName().get()
-            << "\", \"source\":\"\",\n\"phases\":[";
+    {
+      TurboJsonFile json_of(&info, std::ios_base::trunc);
+      json_of << "{\"function\":\"" << info.GetDebugName().get()
+              << "\", \"source\":\"\",\n\"phases\":[";
+    }
     pipeline.Run<PrintGraphPhase>("Machine");
   }