Bug 1432968 - Cache the value of In3DContextAndBackfaceIsHidden during display list buidling. r=miko

--HG--
extra : rebase_source : d22ade7260b9e1ea71837b9a262e2ebd931902b9

layout/painting/FrameLayerBuilder.cpp

@@ -3606,7 +3606,7 @@ ContainerState::NewPaintedLayerData(nsDisplayItem* aItem,
   data.mClipChain = aClipChain;
   data.mAnimatedGeometryRootOffset = aTopLeft;
   data.mReferenceFrame = aItem->ReferenceFrame();
-  data.mBackfaceHidden = aItem->Frame()->In3DContextAndBackfaceIsHidden();
+  data.mBackfaceHidden = aItem->In3DContextAndBackfaceIsHidden();
 
   data.mNewChildLayersIndex = mNewChildLayers.Length();
   NewLayerEntry* newLayerEntry = mNewChildLayers.AppendElement();
@@ -4442,7 +4442,7 @@ ContainerState::ProcessDisplayItems(nsDisplayList* aList)
       PaintedLayerData* paintedLayerData =
         mPaintedLayerDataTree.FindPaintedLayerFor(animatedGeometryRoot, itemASR, layerClipChain,
                                                   itemVisibleRect,
-                                                  item->Frame()->In3DContextAndBackfaceIsHidden(),
+                                                  item->In3DContextAndBackfaceIsHidden(),
                                                   [&]() {
           return NewPaintedLayerData(item, animatedGeometryRoot, itemASR, layerClipChain, scrollMetadataASR,
                                      topLeft);

layout/painting/nsDisplayList.cpp

@@ -2949,6 +2949,7 @@ nsDisplayItem::nsDisplayItem(nsDisplayListBuilder* aBuilder, nsIFrame* aFrame,
   , mForceNotVisible(aBuilder->IsBuildingInvisibleItems())
   , mDisableSubpixelAA(false)
   , mReusedItem(false)
+  , mBackfaceHidden(mFrame->In3DContextAndBackfaceIsHidden())
 #ifdef MOZ_DUMP_PAINTING
   , mPainted(false)
 #endif

layout/painting/nsDisplayList.h

@@ -2003,6 +2003,7 @@ public:
     , mForceNotVisible(false)
     , mDisableSubpixelAA(false)
     , mReusedItem(false)
+    , mBackfaceHidden(mFrame->In3DContextAndBackfaceIsHidden())
 #ifdef MOZ_DUMP_PAINTING
     , mPainted(false)
 #endif
@@ -2074,6 +2075,7 @@ public:
     , mForceNotVisible(aOther.mForceNotVisible)
     , mDisableSubpixelAA(aOther.mDisableSubpixelAA)
     , mReusedItem(false)
+    , mBackfaceHidden(mFrame->In3DContextAndBackfaceIsHidden())
 #ifdef MOZ_DUMP_PAINTING
     , mPainted(false)
 #endif
@@ -2704,16 +2706,7 @@ public:
 
   bool In3DContextAndBackfaceIsHidden()
   {
-    if (mBackfaceHidden) {
-      return *mBackfaceHidden;
-    }
-
-    // We never need to invalidate this cached value since we're
-    // guaranteed to rebuild the display item entirely if it changes.
-    bool backfaceHidden = Frame()->In3DContextAndBackfaceIsHidden();
-    mBackfaceHidden.emplace(backfaceHidden);
-
-    return backfaceHidden;
+    return mBackfaceHidden;
   }
 
   bool HasSameTypeAndClip(const nsDisplayItem* aOther) const
@@ -2774,11 +2767,11 @@ protected:
   bool      mForceNotVisible;
   bool      mDisableSubpixelAA;
   bool      mReusedItem;
+  bool      mBackfaceHidden;
 #ifdef MOZ_DUMP_PAINTING
   // True if this frame has been painted.
   bool      mPainted;
 #endif
-  mozilla::Maybe<bool> mBackfaceHidden;
 
   struct {
     nsRect mVisibleRect;