diff -r 000000000000 -r 6474c204b198 xpcom/string/src/nsTDependentSubstring.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/string/src/nsTDependentSubstring.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+void
+nsTDependentSubstring_CharT::Rebind( const substring_type& str, uint32_t startPos, uint32_t length )
+  {
+    // If we currently own a buffer, release it.
+    Finalize();
+
+    size_type strLength = str.Length();
+
+    if (startPos > strLength)
+      startPos = strLength;
+
+    mData = const_cast<char_type*>(static_cast<const char_type*>(str.Data())) + startPos;
+    mLength = XPCOM_MIN(length, strLength - startPos);
+
+    SetDataFlags(F_NONE);
+  }
+
+void
+nsTDependentSubstring_CharT::Rebind( const char_type* data, size_type length )
+  {
+    NS_ASSERTION(data, "nsTDependentSubstring must wrap a non-NULL buffer");
+
+    // If we currently own a buffer, release it.
+    Finalize();
+
+    mData = const_cast<char_type*>(static_cast<const char_type*>(data));
+    mLength = length;
+    SetDataFlags(F_NONE);
+  }