Set initial vector capacity to 4, down from 16.

Source/wtf/Vector.h

 /*
  *  Copyright (C) 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 20 matching lines @@
 #include <limits>
 #include <utility>
 #include <string.h>
 
 namespace WTF {
 
 #if defined(MEMORY_TOOL_REPLACES_ALLOCATOR)
 static const size_t kInitialVectorSize = 1;
 #else
 #ifndef WTF_VECTOR_INITIAL_SIZE
-#define WTF_VECTOR_INITIAL_SIZE 16
+#define WTF_VECTOR_INITIAL_SIZE 4
 #endif
 static const size_t kInitialVectorSize = WTF_VECTOR_INITIAL_SIZE;
 #endif
 
     template <bool needsDestruction, typename T>
     struct VectorDestructor;
 
     template<typename T>
     struct VectorDestructor<false, T>
     {
@@ skipping 1012 matching lines @@
     inline bool operator!=(const Vector<T, inlineCapacity>& a, const Vector<T, inlineCapacity>& b)
     {
         return !(a == b);
     }
 
 } // namespace WTF
 
 using WTF::Vector;
 
 #endif // WTF_Vector_h