Add Smi::Zero and replace all Smi::FromInt(0) calls

src/objects.h

 // Copyright 2015 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 <memory>
 
@@ skipping 1492 matching lines @@
     DCHECK_EQ(result, value >= kMinValue && value <= kMaxValue);
     return result;
   }
 
   DECLARE_CAST(Smi)
 
   // Dispatched behavior.
   void SmiPrint(std::ostream& os) const;  // NOLINT
   DECLARE_VERIFIER(Smi)
 
+  V8_EXPORT_PRIVATE static Smi* const kZero;
   static const int kMinValue =
       (static_cast<unsigned int>(-1)) << (kSmiValueSize - 1);
   static const int kMaxValue = -(kMinValue + 1);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(Smi);
 };
 
 
 // Heap objects typically have a map pointer in their first word.  However,
@@ skipping 1342 matching lines @@
   };
 
   template <class CompactionCallback>
   void Compact();
 
   inline Object* Get(int index) const;
   inline void Clear(int index);
   inline int Length() const;
 
   inline bool IsEmptySlot(int index) const;
-  static Object* Empty() { return Smi::FromInt(0); }
+  static Object* Empty() { return Smi::kZero; }
 
   class Iterator {
    public:
     explicit Iterator(Object* maybe_array) : list_(NULL) { Reset(maybe_array); }
     void Reset(Object* maybe_array);
 
     template <class T>
     inline T* Next();
 
    private:
@@ skipping 8323 matching lines @@
   static void SetBreakPoint(Handle<DebugInfo> debug_info, int source_position,
                             Handle<Object> break_point_object);
   // Get the break point objects for a source position.
   Handle<Object> GetBreakPointObjects(int source_position);
   // Find the break point info holding this break point object.
   static Handle<Object> FindBreakPointInfo(Handle<DebugInfo> debug_info,
                                            Handle<Object> break_point_object);
   // Get the number of break points for this function.
   int GetBreakPointCount();
 
-  static Smi* uninitialized() { return Smi::FromInt(0); }
+  static Smi* uninitialized() { return Smi::kZero; }
 
   inline bool HasDebugBytecodeArray();
   inline bool HasDebugCode();
 
   inline BytecodeArray* OriginalBytecodeArray();
   inline BytecodeArray* DebugBytecodeArray();
   inline Code* DebugCode();
 
   DECLARE_CAST(DebugInfo)
 
@@ skipping 176 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_