Remove whiteness witness from runtime.

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 2954 matching lines @@
   bool IsEqualTo(DescriptorArray* other);
 #endif
 
   // Returns the fixed array length required to hold number_of_descriptors
   // descriptors.
   static int LengthFor(int number_of_descriptors) {
     return ToKeyIndex(number_of_descriptors);
   }
 
  private:
-  // WhitenessWitness is used to prove that a descriptor array is white
-  // (unmarked), so incremental write barriers can be skipped because the
-  // marking invariant cannot be broken and slots pointing into evacuation
-  // candidates will be discovered when the object is scanned. A witness is
-  // always stack-allocated right after creating an array. By allocating a
-  // witness, incremental marking is globally disabled. The witness is then
-  // passed along wherever needed to statically prove that the array is known to
-  // be white.
-  class WhitenessWitness {
-   public:
-    inline explicit WhitenessWitness(DescriptorArray* array);
-    inline ~WhitenessWitness();
-
-   private:
-    IncrementalMarking* marking_;
-  };
-
   // An entry in a DescriptorArray, represented as an (array, index) pair.
   class Entry {
    public:
     inline explicit Entry(DescriptorArray* descs, int index) :
         descs_(descs), index_(index) { }
 
     inline PropertyType type();
     inline Object* GetCallbackObject();
 
    private:
@@ skipping 15 matching lines @@
   }
 
   static int ToValueIndex(int descriptor_number) {
     return kFirstIndex +
            (descriptor_number * kDescriptorSize) +
            kDescriptorValue;
   }
 
   // Transfer a complete descriptor from the src descriptor array to this
   // descriptor array.
-  void CopyFrom(int index, DescriptorArray* src, const WhitenessWitness&);
+  void CopyFrom(int index, DescriptorArray* src);
 
-  inline void Set(int descriptor_number,
-                  Descriptor* desc,
-                  const WhitenessWitness&);
+  inline void SetDescriptor(int descriptor_number, Descriptor* desc);
 
   // Swap first and second descriptor.
   inline void SwapSortedKeys(int first, int second);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(DescriptorArray);
 };
 
 
 enum SearchMode { ALL_ENTRIES, VALID_ENTRIES };
 
@@ skipping 7697 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_