[perf-prof] fix crash when logging.

src/isolate.h

 // 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.
 
 #ifndef V8_ISOLATE_H_
 #define V8_ISOLATE_H_
 
 #include <memory>
 #include <queue>
 
@@ skipping 948 matching lines @@
     return snapshot_blob_ != NULL && snapshot_blob_->raw_size != 0;
   }
 
   bool IsDead() { return has_fatal_error_; }
   void SignalFatalError() { has_fatal_error_ = true; }
 
   bool use_crankshaft() const;
 
   bool initialized_from_snapshot() { return initialized_from_snapshot_; }
 
+  bool NeedsSourcePositionsForProfiling() const;
+
   double time_millis_since_init() {
     return heap_.MonotonicallyIncreasingTimeInMs() - time_millis_at_init_;
   }
 
   DateCache* date_cache() {
     return date_cache_;
   }
 
   void set_date_cache(DateCache* date_cache) {
     if (date_cache != date_cache_) {
@@ skipping 712 matching lines @@
 
   EmbeddedVector<char, 128> filename_;
   FILE* file_;
   int scope_depth_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_ISOLATE_H_