1 files changed, 16 insertions, 16 deletions

diff --git a/layout/generic/nsSubDocumentFrame.cpp b/layout/generic/nsSubDocumentFrame.cpp
index 47026b73c..215cd5376 100644
--- a/layout/generic/nsSubDocumentFrame.cpp
+++ b/layout/generic/nsSubDocumentFrame.cpp
@@ -327,7 +327,6 @@ WrapBackgroundColorInOwnLayer(nsDisplayListBuilder* aBuilder,
 
 void
 nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
-                                     const nsRect&           aDirtyRect,
                                      const nsDisplayListSet& aLists)
 {
   if (!IsVisibleForPainting(aBuilder))
@@ -368,7 +367,7 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
   }
 
   if (rfp) {
-    rfp->BuildDisplayList(aBuilder, this, aDirtyRect, aLists);
+    rfp->BuildDisplayList(aBuilder, this, aLists);
     return;
   }
 
@@ -393,17 +392,18 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
   nsIFrame* savedIgnoreScrollFrame = nullptr;
   if (subdocRootFrame) {
     // get the dirty rect relative to the root frame of the subdoc
-    dirty = aDirtyRect + GetOffsetToCrossDoc(subdocRootFrame);
+    dirty = aBuilder->GetDirtyRect() + GetOffsetToCrossDoc(subdocRootFrame);
     // and convert into the appunits of the subdoc
     dirty = dirty.ScaleToOtherAppUnitsRoundOut(parentAPD, subdocAPD);
 
     if (nsIFrame* rootScrollFrame = presShell->GetRootScrollFrame()) {
       nsIScrollableFrame* rootScrollableFrame = presShell->GetRootScrollFrameAsScrollable();
       MOZ_ASSERT(rootScrollableFrame);
-      // Use a copy, so the dirty rect doesn't get modified to the display port.
-      nsRect copy = dirty;
+      // Use a copy, so the rects don't get modified.
+      nsRect copyOfDirty = dirty;
       haveDisplayPort = rootScrollableFrame->DecideScrollableLayer(aBuilder,
-                          &copy, /* aAllowCreateDisplayPort = */ true);
+                           &copyOfDirty,
+                          /* aAllowCreateDisplayPort = */ true);
       if (!gfxPrefs::LayoutUseContainersForRootFrames()) {
         haveDisplayPort = false;
       }
@@ -417,7 +417,7 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 
     aBuilder->EnterPresShell(subdocRootFrame, pointerEventsNone);
   } else {
-    dirty = aDirtyRect;
+    dirty = aBuilder->GetDirtyRect();
   }
 
   DisplayListClipState::AutoSaveRestore clipState(aBuilder);
@@ -456,6 +456,13 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
       nestedClipState.EnterStackingContextContents(true);
     }
 
+    // Invoke AutoBuildingDisplayList to ensure that the correct dirty rect
+    // is used to compute the visible rect if AddCanvasBackgroundColorItem
+    // creates a display item.
+    nsIFrame* frame = subdocRootFrame ? subdocRootFrame : this;
+    nsDisplayListBuilder::AutoBuildingDisplayList
+      building(aBuilder, frame, dirty, true);
+
     if (subdocRootFrame) {
       nsIFrame* rootScrollFrame = presShell->GetRootScrollFrame();
       nsDisplayListBuilder::AutoCurrentScrollParentIdSetter idSetter(
@@ -466,7 +473,7 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
 
       aBuilder->SetAncestorHasApzAwareEventHandler(false);
       subdocRootFrame->
-        BuildDisplayListForStackingContext(aBuilder, dirty, &childItems);
+        BuildDisplayListForStackingContext(aBuilder, &childItems);
     }
 
     if (!aBuilder->IsForEventDelivery()) {
@@ -485,15 +492,8 @@ nsSubDocumentFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
       // painted on the page itself.
       if (nsLayoutUtils::NeedsPrintPreviewBackground(presContext)) {
         presShell->AddPrintPreviewBackgroundItem(
-          *aBuilder, childItems, subdocRootFrame ? subdocRootFrame : this,
-          bounds);
+          *aBuilder, childItems, frame, bounds);
       } else {
-        // Invoke AutoBuildingDisplayList to ensure that the correct dirty rect
-        // is used to compute the visible rect if AddCanvasBackgroundColorItem
-        // creates a display item.
-        nsIFrame* frame = subdocRootFrame ? subdocRootFrame : this;
-        nsDisplayListBuilder::AutoBuildingDisplayList
-          building(aBuilder, frame, dirty, true);
         // Add the canvas background color to the bottom of the list. This
         // happens after we've built the list so that AddCanvasBackgroundColorItem
         // can monkey with the contents if necessary.