--- a/gfx/layers/wr/StackingContextHelper.cpp
+++ b/gfx/layers/wr/StackingContextHelper.cpp
@@ -22,36 +22,36 @@ StackingContextHelper::StackingContextHe
                                              wr::DisplayListBuilder& aBuilder,
                                              const nsTArray<wr::WrFilterOp>& aFilters,
                                              const gfx::Matrix4x4* aBoundTransform,
                                              uint64_t aAnimationsId,
                                              float* aOpacityPtr,
                                              gfx::Matrix4x4* aTransformPtr,
                                              gfx::Matrix4x4* aPerspectivePtr,
                                              const gfx::CompositionOp& aMixBlendMode,
-                                             bool aBackfaceVisible)
+                                             bool aBackfaceVisible,
+                                             bool aIsPreserve3D)
   : mBuilder(&aBuilder)
   , mScale(1.0f, 1.0f)
 {
-  bool is2d = !aTransformPtr || (aTransformPtr->Is2D() && !aPerspectivePtr);
   if (aTransformPtr) {
     mTransform = *aTransformPtr;
   }
 
   // Compute scale for fallback rendering.
   gfx::Matrix transform2d;
   if (aBoundTransform && aBoundTransform->CanDraw2D(&transform2d)) {
     mScale = transform2d.ScaleFactors(true) * aParentSC.mScale;
   }
 
   mBuilder->PushStackingContext(wr::LayoutRect(),
                                 aAnimationsId,
                                 aOpacityPtr,
                                 aTransformPtr,
-                                is2d ? wr::TransformStyle::Flat : wr::TransformStyle::Preserve3D,
+                                aIsPreserve3D ? wr::TransformStyle::Preserve3D : wr::TransformStyle::Flat,
                                 aPerspectivePtr,
                                 wr::ToMixBlendMode(aMixBlendMode),
                                 aFilters,
                                 aBackfaceVisible);
 }
 
 StackingContextHelper::~StackingContextHelper()
 {

--- a/gfx/layers/wr/StackingContextHelper.h
+++ b/gfx/layers/wr/StackingContextHelper.h
@@ -32,17 +32,18 @@ public:
                         wr::DisplayListBuilder& aBuilder,
                         const nsTArray<wr::WrFilterOp>& aFilters = nsTArray<wr::WrFilterOp>(),
                         const gfx::Matrix4x4* aBoundTransform = nullptr,
                         uint64_t aAnimationsId = 0,
                         float* aOpacityPtr = nullptr,
                         gfx::Matrix4x4* aTransformPtr = nullptr,
                         gfx::Matrix4x4* aPerspectivePtr = nullptr,
                         const gfx::CompositionOp& aMixBlendMode = gfx::CompositionOp::OP_OVER,
-                        bool aBackfaceVisible = true);
+                        bool aBackfaceVisible = true,
+                        bool aIsPreserve3D = false);
   // This version of the constructor should only be used at the root level
   // of the tree, so that we have a StackingContextHelper to pass down into
   // the RenderLayer traversal, but don't actually want it to push a stacking
   // context on the display list builder.
   StackingContextHelper();
 
   // Pops the stacking context, if one was pushed during the constructor.
   ~StackingContextHelper();

--- a/layout/painting/nsDisplayList.cpp
+++ b/layout/painting/nsDisplayList.cpp
@@ -8059,17 +8059,18 @@ nsDisplayTransform::CreateWebRenderComma
                            aBuilder,
                            filters,
                            &newTransformMatrix,
                            animationsId,
                            nullptr,
                            transformForSC,
                            nullptr,
                            gfx::CompositionOp::OP_OVER,
-                           !BackfaceIsHidden());
+                           !BackfaceIsHidden(),
+                           mFrame->Extend3DContext());
 
   return mStoredList.CreateWebRenderCommands(aBuilder, aResources, sc,
                                              aManager, aDisplayListBuilder);
 }
 
 bool
 nsDisplayTransform::UpdateScrollData(mozilla::layers::WebRenderScrollData* aData,
                                      mozilla::layers::WebRenderLayerScrollData* aLayerData)
@@ -8670,17 +8671,18 @@ nsDisplayPerspective::CreateWebRenderCom
                            aBuilder,
                            filters,
                            nullptr,
                            0,
                            nullptr,
                            &transformForSC,
                            &perspectiveMatrix,
                            gfx::CompositionOp::OP_OVER,
-                           !BackfaceIsHidden());
+                           !BackfaceIsHidden(),
+                           true);
 
   return mList.CreateWebRenderCommands(aBuilder, aResources, sc,
                                        aManager, aDisplayListBuilder);
 }
 
 int32_t
 nsDisplayPerspective::ZIndex() const
 {

--- a/layout/reftests/transform-3d/reftest.list
+++ b/layout/reftests/transform-3d/reftest.list
@@ -44,17 +44,17 @@ fuzzy-if(winWidget&&!layersGPUAccelerate
 fuzzy-if(webrender,0-1,0-3) == perspective-origin-1b.html perspective-origin-1a.html
 fuzzy(3,99) random-if(Android&&!browserIsRemote) == perspective-origin-2a.html perspective-origin-2-ref.html # subpixel AA, bug 732568
 fuzzy-if(winWidget&&!layersGPUAccelerated,1,61) == perspective-origin-3a.html perspective-origin-3-ref.html
 == perspective-origin-4a.html perspective-origin-4-ref.html
 == perspective-zindex.html green-rect.html
 == perspective-zindex-2.html green-rect.html
 != sorting-1a.html sorting-1-ref.html
 # Parallel planes, different z depth
-fails-if(webrender) == sorting-2a.html sorting-2-ref.html
+== sorting-2a.html sorting-2-ref.html
 # Parallel planes, same z depth (shouldn't be sorted!)
 == sorting-2b.html sorting-2-ref.html
 == sorting-3a.html green-rect.html
 # Different, but equivalent (for the given transform) transform origins
 fuzzy-if(webrender,0-1,0-2) == rotatex-transformorigin-1a.html rotatex-transformorigin-1-ref.html
 fuzzy-if((gtkWidget&&layersOMTC)||(winWidget&&!layersGPUAccelerated),1,86) == overflow-hidden-1a.html overflow-hidden-1-ref.html
 fails-if(webrender) == transform-style-flat-1a.html transform-style-flat-1-ref.html
 == willchange-containing-block.html?willchange willchange-containing-block.html?ref
@@ -79,14 +79,14 @@ fuzzy(1,15000) == opacity-preserve3d-2.h
 fuzzy(1,10000) == opacity-preserve3d-3.html opacity-preserve3d-3-ref.html
 fuzzy(1,10000) == opacity-preserve3d-4.html opacity-preserve3d-4-ref.html
 == opacity-preserve3d-5.html opacity-preserve3d-5-ref.html
 == snap-perspective-1.html snap-perspective-1-ref.html
 == mask-layer-1.html mask-layer-ref.html
 == mask-layer-2.html mask-layer-ref.html
 fails-if(webrender) == mask-layer-3.html mask-layer-ref.html
 fails-if(webrender) == split-intersect1.html split-intersect1-ref.html
-fuzzy(255,150) fails-if(webrender) == split-intersect2.html split-intersect2-ref.html
+fuzzy(255,150) == split-intersect2.html split-intersect2-ref.html
 fuzzy(255,100) fails-if(webrender) == split-non-ortho1.html split-non-ortho1-ref.html
 fuzzy-if(winWidget,150,120) == component-alpha-1.html component-alpha-1-ref.html
 == nested-transform-1.html nested-transform-1-ref.html
 == transform-geometry-1.html transform-geometry-1-ref.html
 == intermediate-1.html intermediate-1-ref.html