--- a/layout/style/nsCSSValue.h
+++ b/layout/style/nsCSSValue.h
@@ -3,18 +3,16 @@
  * 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/. */
 
 /* representation of simple property values within CSS declarations */
 
 #ifndef nsCSSValue_h___
 #define nsCSSValue_h___
 
-#include <type_traits>
-
 #include "mozilla/Attributes.h"
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/SheetType.h"
 #include "mozilla/StyleComplexColor.h"
 #include "mozilla/UniquePtr.h"
 
 #include "nsIPrincipal.h"
 #include "nsIURI.h"
@@ -28,16 +26,18 @@
 #include "nsRefPtrHashtable.h"
 #include "nsString.h"
 #include "nsStringBuffer.h"
 #include "nsTArray.h"
 #include "nsStyleConsts.h"
 #include "nsStyleCoord.h"
 #include "gfxFontFamilyList.h"
 
+#include <type_traits>
+
 class imgRequestProxy;
 class nsIContent;
 class nsIDocument;
 class nsIPrincipal;
 class nsIURI;
 class nsPresContext;
 template <class T>
 class nsPtrHashKey;