--- a/layout/base/RestyleManagerBase.cpp
+++ b/layout/base/RestyleManagerBase.cpp
@@ -148,17 +148,17 @@ RestyleManagerBase::ChangeHintToString(n
     "UpdateCursor", "UpdateEffects", "UpdateOpacityLayer",
     "UpdateTransformLayer", "ReconstructFrame", "UpdateOverflow",
     "UpdateSubtreeOverflow", "UpdatePostTransformOverflow",
     "UpdateParentOverflow",
     "ChildrenOnlyTransform", "RecomputePosition", "AddOrRemoveTransform",
     "BorderStyleNoneChange", "UpdateTextPath", "SchedulePaint",
     "NeutralChange", "InvalidateRenderingObservers",
     "ReflowChangesSizeOrPosition", "UpdateComputedBSize",
-    "UpdateUsesOpacity"
+    "UpdateUsesOpacity", "UpdateBackgroundPosition"
   };
   uint32_t hint = aHint & ((1 << ArrayLength(names)) - 1);
   uint32_t rest = aHint & ~((1 << ArrayLength(names)) - 1);
   if (hint == nsChangeHint_Hints_NotHandledForDescendants) {
     result.AppendLiteral("nsChangeHint_Hints_NotHandledForDescendants");
     hint = 0;
     any = true;
   } else {