[turbofan] Allow handle deferences when compiling non concurrently

When FLAG_noconcurrent_recompilation is turned on we always run on main
thread. So it is safe to derefernce handles when printing the turbofan
graph. We should only add a DCHECK when dereferencing read-only heap
objects when optimizing concurrently.

Bug: chromium:1040444,chromium:1040403
Change-Id: I6bde966690458b1d122611b02e713c581c87f534
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1992433Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65659}

src/compiler/js-heap-broker.cc

@@ -5057,6 +5057,10 @@ std::ostream& operator<<(std::ostream& os, const ObjectRef& ref) {
   if (ref.data_->kind() == ObjectDataKind::kUnserializedHeapObject ||
       !FLAG_concurrent_recompilation) {
     // We cannot be in a background thread so it's safe to read the heap.
+    AllowHandleDereference allow_handle_dereference;
+    return os << ref.data() << " {" << ref.object() << "}";
+  } else if (ref.data_->kind() ==
+             ObjectDataKind::kUnserializedReadOnlyHeapObject) {
     AllowHandleDereferenceIf allow_handle_dereference(ref.data()->kind(),
                                                       ref.broker()->mode());
     return os << ref.data() << " {" << ref.object() << "}";

test/mjsunit/regress/regress-1040403.js

+// Copyright 2020 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.
+//
+// Flags: --allow-natives-syntax --trace-turbo-graph --noconcurrent-recompilation
+
+function bytes() {
+}
+function __f_4622() {
+  var __v_22507 = {
+  };
+}
+%PrepareFunctionForOptimization(__f_4622);
+%OptimizeFunctionOnNextCall(__f_4622);
+42 |  __f_4622();