diff -r 000000000000 -r 6474c204b198 layout/base/nsStyleChangeList.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/base/nsStyleChangeList.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,72 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+/*
+ * a list of the recomputation that needs to be done in response to a
+ * style change
+ */
+
+#ifndef nsStyleChangeList_h___
+#define nsStyleChangeList_h___
+
+#include "mozilla/Attributes.h"
+
+#include "nsError.h"
+#include "nsChangeHint.h"
+
+class nsIFrame;
+class nsIContent;
+
+// XXX would all platforms support putting this inside the list?
+struct nsStyleChangeData {
+  nsIFrame*   mFrame;
+  nsIContent* mContent;
+  nsChangeHint mHint;
+};
+
+static const uint32_t kStyleChangeBufferSize = 10;
+
+// Note:  nsStyleChangeList owns a reference to
+//  nsIContent pointers in its list.
+class nsStyleChangeList {
+public:
+  nsStyleChangeList();
+  ~nsStyleChangeList();
+
+  int32_t Count(void) const {
+    return mCount;
+  }
+
+  /**
+   * Fills in pointers without reference counting.  
+   */
+  nsresult ChangeAt(int32_t aIndex, nsIFrame*& aFrame, nsIContent*& aContent,
+                    nsChangeHint& aHint) const;
+
+  /**
+   * Fills in a pointer to the list entry storage (no reference counting
+   * involved).
+   */
+  nsresult ChangeAt(int32_t aIndex, const nsStyleChangeData** aChangeData) const;
+
+  nsresult AppendChange(nsIFrame* aFrame, nsIContent* aContent, nsChangeHint aHint);
+
+  void Clear(void);
+
+protected:
+  nsStyleChangeList&  operator=(const nsStyleChangeList& aCopy);
+  bool                operator==(const nsStyleChangeList& aOther) const;
+
+  nsStyleChangeData*  mArray;
+  int32_t             mArraySize;
+  int32_t             mCount;
+  nsStyleChangeData   mBuffer[kStyleChangeBufferSize];
+
+private:
+  nsStyleChangeList(const nsStyleChangeList&) MOZ_DELETE;
+};
+
+
+#endif /* nsStyleChangeList_h___ */