[heap] Remove remaining parts of PathTracer.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 3aa26c5601690e1ae5e5270cd1e268abb0cdc1ec..8db7434eee532591a53880b699079075f496f767 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -1457,14 +1457,7 @@ Isolate* HeapObject::GetIsolate() const {
 
 
 Map* HeapObject::map() const {
-#ifdef DEBUG
-  // Clear mark potentially added by PathTracer.
-  uintptr_t raw_value =
-      map_word().ToRawValue() & ~static_cast<uintptr_t>(PathTracer::kMarkTag);
-  return MapWord::FromRawValue(raw_value).ToMap();
-#else
   return map_word().ToMap();
-#endif
 }