Fix warnings on Win64.

src/list.h

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 41 matching lines @@
   INLINE(explicit List(int capacity)) { Initialize(capacity); }
   INLINE(~List()) { DeleteData(data_); }
 
   // Deallocates memory used by the list and leaves the list in a consistent
   // empty state.
   void Free() {
     DeleteData(data_);
     Initialize(0);
   }
 
-  INLINE(void* operator new(size_t size)) { return P::New(size); }
+  INLINE(void* operator new(size_t size)) {
+      return P::New(static_cast<int>(size));
+  }
   INLINE(void operator delete(void* p, size_t)) { return P::Delete(p); }
 
   // Returns a reference to the element at index i.  This reference is
   // not safe to use after operations that can change the list's
   // backing store (eg, Add).
   inline T& operator[](int i) const  {
     ASSERT(0 <= i && i < length_);
     return data_[i];
   }
   inline T& at(int i) const  { return operator[](i); }
@@ skipping 74 matching lines @@
 
 // Add() is inlined, ResizeAdd() called by Add() is inlined except for
 // Lists of FrameElements, and ResizeAddInternal() is inlined in ResizeAdd().
 template <>
 void List<FrameElement,
           FreeStoreAllocationPolicy>::ResizeAdd(const FrameElement& element);
 
 } }  // namespace v8::internal
 
 #endif  // V8_LIST_H_