diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index c48d9f963019..d8afd51b974d 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -1681,6 +1681,14 @@ void nsCSSFrameConstructor::CreateGeneratedContentFromListStyleType(
   aAddChild(child);
 }
 
+// Frames for these may not be leaves in the proper sense, but we still don't
+// want to expose generated content on them. For the purposes of the page they
+// should be leaves.
+static bool HasUAWidget(const Element& aOriginatingElement) {
+  const ShadowRoot* sr = aOriginatingElement.GetShadowRoot();
+  return sr && sr->IsUAWidget();
+}
+
 /*
  * aParentFrame - the frame that should be the parent of the generated
  *   content.  This is the frame for the corresponding content node,
@@ -1705,10 +1713,7 @@ void nsCSSFrameConstructor::CreateGeneratedContentItem(
                  aPseudoElement == PseudoStyleType::marker,
              "unexpected aPseudoElement");
 
-  if (aParentFrame && (aParentFrame->IsHTMLVideoFrame() ||
-                       aParentFrame->IsDateTimeControlFrame())) {
-    // Video frames and date time control frames may not be leafs when backed by
-    // an UA widget, but we still don't want to expose generated content.
+  if (HasUAWidget(aOriginatingElement)) {
     return;
   }
 
diff --git a/layout/generic/FrameClass.py b/layout/generic/FrameClass.py
index 00a57abb7f27..0fae9e115efd 100644
--- a/layout/generic/FrameClass.py
+++ b/layout/generic/FrameClass.py
@@ -6,6 +6,7 @@
 # Leaf constants to pass to Frame's leafness argument.
 LEAF = "Leaf"
 NOT_LEAF = "NotLeaf"
+DYNAMIC_LEAF = "DynamicLeaf"
 
 
 class FrameClass:
diff --git a/layout/generic/FrameClasses.py b/layout/generic/FrameClasses.py
index e244974bfe9c..67f685a1460c 100644
--- a/layout/generic/FrameClasses.py
+++ b/layout/generic/FrameClasses.py
@@ -3,7 +3,7 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 # Frame class definitions, used to generate FrameIdList.h and FrameTypeList.h
 
-from FrameClass import Frame, AbstractFrame, LEAF, NOT_LEAF
+from FrameClass import Frame, AbstractFrame, LEAF, NOT_LEAF, DYNAMIC_LEAF
 
 FRAME_CLASSES = [
     Frame("BRFrame", "Br", LEAF),
@@ -41,7 +41,7 @@ FRAME_CLASSES = [
     Frame("nsHTMLScrollFrame", "Scroll", NOT_LEAF),
     Frame("nsImageBoxFrame", "ImageBox", LEAF),
     Frame("nsImageControlFrame", "ImageControl", LEAF),
-    Frame("nsImageFrame", "Image", LEAF),
+    Frame("nsImageFrame", "Image", DYNAMIC_LEAF),
     Frame("nsInlineFrame", "Inline", NOT_LEAF),
     Frame("nsLeafBoxFrame", "LeafBox", LEAF),
     Frame("nsListControlFrame", "ListControl", NOT_LEAF),
diff --git a/layout/generic/nsIFrame.cpp b/layout/generic/nsIFrame.cpp
index a71d2ade036e..82a204e0bd20 100644
--- a/layout/generic/nsIFrame.cpp
+++ b/layout/generic/nsIFrame.cpp
@@ -171,11 +171,13 @@ const nsIFrame::FrameClassBits nsIFrame::sFrameClassBits[
     0] = {
 #define Leaf eFrameClassBitsLeaf
 #define NotLeaf eFrameClassBitsNone
+#define DynamicLeaf eFrameClassBitsDynamicLeaf
 #define FRAME_ID(class_, type_, leaf_, ...) leaf_,
 #define ABSTRACT_FRAME_ID(...)
 #include "mozilla/FrameIdList.h"
 #undef Leaf
 #undef NotLeaf
+#undef DynamicLeaf
 #undef FRAME_ID
 #undef ABSTRACT_FRAME_ID
 };
diff --git a/layout/generic/nsIFrame.h b/layout/generic/nsIFrame.h
index dcfba6cb8ee3..0110377976d3 100644
--- a/layout/generic/nsIFrame.h
+++ b/layout/generic/nsIFrame.h
@@ -3366,9 +3366,14 @@ class nsIFrame : public nsQueryFrame {
   bool IsLeaf() const {
     MOZ_ASSERT(uint8_t(mClass) < mozilla::ArrayLength(sFrameClassBits));
     FrameClassBits bits = sFrameClassBits[uint8_t(mClass)];
+    if (MOZ_UNLIKELY(bits & eFrameClassBitsDynamicLeaf)) {
+      return IsLeafDynamic();
+    }
     return bits & eFrameClassBitsLeaf;
   }
 
+  virtual bool IsLeafDynamic() const { return false; }
+
   /**
    * Marks all display items created by this frame as needing a repaint,
    * and calls SchedulePaint() if requested and one is not already pending.
@@ -5413,6 +5418,7 @@ class nsIFrame : public nsQueryFrame {
   enum FrameClassBits {
     eFrameClassBitsNone = 0x0,
     eFrameClassBitsLeaf = 0x1,
+    eFrameClassBitsDynamicLeaf = 0x2,
   };
   // Maps mClass to IsLeaf() flags.
   static const FrameClassBits sFrameClassBits[
diff --git a/layout/generic/nsImageFrame.cpp b/layout/generic/nsImageFrame.cpp
index 4a09b9991a19..da860cbc156d 100644
--- a/layout/generic/nsImageFrame.cpp
+++ b/layout/generic/nsImageFrame.cpp
@@ -1209,6 +1209,31 @@ nscoord nsImageFrame::GetPrefISize(gfxContext* aRenderingContext) {
   return iSize.valueOr(0);
 }
 
+void nsImageFrame::ReflowChildren(nsPresContext* aPresContext,
+                                  const ReflowInput& aReflowInput,
+                                  const LogicalSize& aImageSize) {
+  for (nsIFrame* child : mFrames) {
+    ReflowOutput childDesiredSize(aReflowInput);
+    WritingMode wm = GetWritingMode();
+    // Shouldn't be hard to support if we want, but why bother.
+    MOZ_ASSERT(
+        wm == child->GetWritingMode(),
+        "We don't expect mismatched writing-modes in content we control");
+    nsReflowStatus childStatus;
+
+    LogicalPoint childOffset(wm);
+    ReflowInput childReflowInput(aPresContext, aReflowInput, child, aImageSize);
+    const nsSize containerSize = aImageSize.GetPhysicalSize(wm);
+    ReflowChild(child, aPresContext, childDesiredSize, childReflowInput, wm,
+                childOffset, containerSize, ReflowChildFlags::Default,
+                childStatus);
+
+    FinishReflowChild(child, aPresContext, childDesiredSize, &childReflowInput,
+                      wm, childOffset, containerSize,
+                      ReflowChildFlags::Default);
+  }
+}
+
 void nsImageFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
                           const ReflowInput& aReflowInput,
                           nsReflowStatus& aStatus) {
@@ -1296,6 +1321,9 @@ void nsImageFrame::Reflow(nsPresContext* aPresContext, ReflowOutput& aMetrics,
   }
   FinishAndStoreOverflow(&aMetrics, aReflowInput.mStyleDisplay);
 
+  // Reflow the child frames. Our children can't affect our size in any way.
+  ReflowChildren(aPresContext, aReflowInput, aMetrics.Size(GetWritingMode()));
+
   if (HasAnyStateBits(NS_FRAME_FIRST_REFLOW) && !mReflowCallbackPosted) {
     mReflowCallbackPosted = true;
     PresShell()->PostReflowCallback(this);
@@ -2326,6 +2354,8 @@ void nsImageFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
     DisplaySelectionOverlay(aBuilder, aLists.Content(),
                             nsISelectionDisplay::DISPLAY_IMAGES);
   }
+
+  BuildDisplayListForNonBlockChildren(aBuilder, aLists);
 }
 
 bool nsImageFrame::ShouldDisplaySelection() {
@@ -2400,6 +2430,19 @@ bool nsImageFrame::GetAnchorHREFTargetAndNode(nsIURI** aHref, nsString& aTarget,
   return status;
 }
 
+bool nsImageFrame::IsLeafDynamic() const {
+  if (mKind != Kind::ImageElement) {
+    // Image frames created for "content: url()" could have an author-controlled
+    // shadow root, we want to be a regular leaf for those.
+    return true;
+  }
+  // For elements that create image frames, calling attachShadow() will throw,
+  // so the only ShadowRoot we could ever have is a UA widget.
+  const auto* shadow = mContent->AsElement()->GetShadowRoot();
+  MOZ_ASSERT_IF(shadow, shadow->IsUAWidget());
+  return !shadow;
+}
+
 nsresult nsImageFrame::GetContentForEvent(WidgetEvent* aEvent,
                                           nsIContent** aContent) {
   NS_ENSURE_ARG_POINTER(aContent);
diff --git a/layout/generic/nsImageFrame.h b/layout/generic/nsImageFrame.h
index e90c5c480055..2012cbfb5f1a 100644
--- a/layout/generic/nsImageFrame.h
+++ b/layout/generic/nsImageFrame.h
@@ -84,6 +84,7 @@ class nsImageFrame : public nsAtomicContainerFrame, public nsIReflowCallback {
   }
   void Reflow(nsPresContext*, ReflowOutput&, const ReflowInput&,
               nsReflowStatus&) override;
+  bool IsLeafDynamic() const override;
 
   nsresult GetContentForEvent(mozilla::WidgetEvent*,
                               nsIContent** aContent) final;
@@ -212,6 +213,9 @@ class nsImageFrame : public nsAtomicContainerFrame, public nsIReflowCallback {
 
   nsImageFrame(ComputedStyle*, nsPresContext* aPresContext, ClassID, Kind);
 
+  void ReflowChildren(nsPresContext*, const ReflowInput&,
+                      const mozilla::LogicalSize& aImageSize);
+
  protected:
   nsImageFrame(ComputedStyle* aStyle, nsPresContext* aPresContext, ClassID aID)
       : nsImageFrame(aStyle, aPresContext, aID, Kind::ImageElement) {}