Avoid manual object's body traversal in GC.

src/objects.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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 1486 matching lines @@
  private:
   // HeapObject calls the private constructor and directly reads the value.
   friend class HeapObject;
 
   explicit MapWord(uintptr_t value) : value_(value) {}
 
   uintptr_t value_;
 };
 
 
-// The content of an heap object (except for the map pointer). kTaggedValues
-// objects can contain both heap pointers and Smis, kMixedValues can contain
-// heap pointers, Smis, and raw values (e.g. doubles or strings), and kRawValues
-// objects can contain raw values and Smis.
-enum class HeapObjectContents { kTaggedValues, kMixedValues, kRawValues };
-
-
 // HeapObject is the superclass for all classes describing heap allocated
 // objects.
 class HeapObject: public Object {
  public:
   // [map]: Contains a map which contains the object's reflective
   // information.
   inline Map* map() const;
   inline void set_map(Map* value);
   // The no-write-barrier version.  This is OK if the object is white and in
   // new space, or if the value is an immortal immutable object, like the maps
@@ skipping 56 matching lines @@
                               ObjectVisitor* v);
 
   // Returns true if the object contains a tagged value at given offset.
   // It is used for invalid slots filtering. If the offset points outside
   // of the object or to the map word, the result is UNDEFINED (!!!).
   bool IsValidSlot(int offset);
 
   // Returns the heap object's size in bytes
   inline int Size();
 
-  // Indicates what type of values this heap object may contain.
-  inline HeapObjectContents ContentType();
-
   // Given a heap object's map pointer, returns the heap size in bytes
   // Useful when the map pointer field is used for other purposes.
   // GC internal.
   inline int SizeFromMap(Map* map);
 
   // Returns the field at offset in obj, as a read/write Object* reference.
   // Does no checking, and is safe to use during GC, while maps are invalid.
   // Does not invoke write barrier, so should only be assigned to
   // during marking GC.
   static inline Object** RawField(HeapObject* obj, int offset);
@@ skipping 9105 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_