Fix for LinkedHashSet::swap.

Source/wtf/LinkedHashSet.h

 /*
  * Copyright (C) 2005, 2006, 2007, 2008, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011, Benjamin Poulain <ikipou@gmail.com>
  *
  * 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,
@@ skipping 481 matching lines @@
 {
     LinkedHashSet tmp(other);
     swap(tmp);
     return *this;
 }
 
 template<typename T, typename U, typename V, typename W>
 inline void LinkedHashSet<T, U, V, W>::swap(LinkedHashSet& other)
 {
     m_impl.swap(other.m_impl);
-    swap(m_anchor, other.m_anchor);
+    swapAnchor(m_anchor, other.m_anchor);
 }
 
 template<typename T, typename U, typename V, typename Allocator>
 inline LinkedHashSet<T, U, V, Allocator>::~LinkedHashSet()
 {
     // The destructor of m_anchor will implicitly be called here, which will
     // unlink the anchor from the collection.
 }
 
 template<typename T, typename U, typename V, typename W>
@@ skipping 147 matching lines @@
         return;
     m_impl.remove(it.node());
 }
 
 template<typename T, typename U, typename V, typename W>
 inline void LinkedHashSet<T, U, V, W>::remove(ValuePeekInType value)
 {
     remove(find(value));
 }
 
+inline void swapAnchor(LinkedHashSetNodeBase& a, LinkedHashSetNodeBase& b)
+{
+    ASSERT(a.m_prev && a.m_next && b.m_prev && b.m_next);
+    swap(a.m_prev, b.m_prev);
+    swap(a.m_next, b.m_next);
+    if (b.m_next == &a) {
+        ASSERT(b.m_prev == &a);
+        b.m_next = &b;
+        b.m_prev = &b;
+    } else {
+        b.m_next->m_prev = &b;
+        b.m_prev->m_next = &b;
+    }
+    if (a.m_next == &b) {
+        ASSERT(a.m_prev == &b);
+        a.m_next = &a;
+        a.m_prev = &a;
+    } else {
+        a.m_next->m_prev = &a;
+        a.m_prev->m_next = &a;
+    }
+}
+
 inline void swap(LinkedHashSetNodeBase& a, LinkedHashSetNodeBase& b)
 {
+    ASSERT(a.m_next != &a && b.m_next != &b);
     swap(a.m_prev, b.m_prev);
     swap(a.m_next, b.m_next);
     if (b.m_next) {
         b.m_next->m_prev = &b;
         b.m_prev->m_next = &b;
     }
     if (a.m_next) {
         a.m_next->m_prev = &a;
         a.m_prev->m_next = &a;
     }
@@ skipping 25 matching lines @@
 struct NeedsTracing<LinkedHashSet<T, U, V> > {
     static const bool value = false;
 };
 #endif
 
 }
 
 using WTF::LinkedHashSet;
 
 #endif /* WTF_LinkedHashSet_h */