--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -1037,21 +1037,21 @@ GetDisplayPortImpl(nsIContent* aContent,
       rectData = nullptr;
     }
   }
 
   NS_ASSERTION((rectData == nullptr) != (marginsData == nullptr),
                "Only one of rectData or marginsData should be set!");
 
   nsRect result;
-  if (APZCCallbackHelper::IsDisplayportSuppressed()) {
+  if (rectData) {
+    result = GetDisplayPortFromRectData(aContent, rectData, aMultiplier);
+  } else if (APZCCallbackHelper::IsDisplayportSuppressed()) {
     DisplayPortMarginsPropertyData noMargins(ScreenMargin(), 1);
     result = GetDisplayPortFromMarginsData(aContent, &noMargins, aMultiplier);
-  } else if (rectData) {
-    result = GetDisplayPortFromRectData(aContent, rectData, aMultiplier);
   } else {
     result = GetDisplayPortFromMarginsData(aContent, marginsData, aMultiplier);
   }
 
   if (!gfxPrefs::LayersTilesEnabled()) {
     // Either we should have gotten a valid rect directly from the displayport
     // base, or we should have computed a valid rect from the margins.
     NS_ASSERTION(result.width <= GetMaxDisplayPortSize(aContent),