Make UsingEmbedderHeapTracer nicer

src/heap/heap.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_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 1187 matching lines @@
   void RegisterReservationsForBlackAllocation(Reservation* reservations);
 
   IncrementalMarking* incremental_marking() { return incremental_marking_; }
 
   // ===========================================================================
   // Embedder heap tracer support. =============================================
   // ===========================================================================
 
   void SetEmbedderHeapTracer(EmbedderHeapTracer* tracer);
 
-  bool UsingEmbedderHeapTracer() { return embedder_heap_tracer(); }
+  bool UsingEmbedderHeapTracer() { return embedder_heap_tracer() != nullptr; }
 
   void TracePossibleWrapper(JSObject* js_object);
 
   void RegisterExternallyReferencedObject(Object** object);
 
   void RegisterWrappersWithEmbedderHeapTracer();
 
   // In order to avoid running out of memory we force tracing wrappers if there
   // are too many of them.
   bool RequiresImmediateWrapperProcessing();
@@ skipping 1419 matching lines @@
   }
 
  private:
   Heap* heap_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_