Bug 1728251 - Remove FuseClipChainUpTo since its unused. r=miko

Differential Revision: https://phabricator.services.mozilla.com/D124007

layout/painting/nsDisplayList.cpp

@@ -1579,26 +1579,6 @@ const DisplayItemClipChain* nsDisplayListBuilder::CopyWholeChain(
   return CreateClipChainIntersection(nullptr, aClipChain, nullptr);
 }
 
-const DisplayItemClipChain* nsDisplayListBuilder::FuseClipChainUpTo(
-    const DisplayItemClipChain* aClipChain, const ActiveScrolledRoot* aASR) {
-  if (!aClipChain) {
-    return nullptr;
-  }
-
-  const DisplayItemClipChain* sc = aClipChain;
-  DisplayItemClip mergedClip;
-  while (sc && ActiveScrolledRoot::PickDescendant(aASR, sc->mASR) == sc->mASR) {
-    mergedClip.IntersectWith(sc->mClip);
-    sc = sc->mParent;
-  }
-
-  if (!mergedClip.HasClip()) {
-    return nullptr;
-  }
-
-  return AllocateDisplayItemClipChain(mergedClip, aASR, sc);
-}
-
 const nsIFrame* nsDisplayListBuilder::FindReferenceFrameFor(
     const nsIFrame* aFrame, nsPoint* aOffset) const {
   auto MaybeApplyAdditionalOffset = [&]() {
@@ -2844,17 +2824,6 @@ Maybe<nsRect> nsDisplayItem::GetClipWithRespectToASR(
   return Nothing();
 }
 
-void nsDisplayItem::FuseClipChainUpTo(nsDisplayListBuilder* aBuilder,
-                                      const ActiveScrolledRoot* aASR) {
-  mClipChain = aBuilder->FuseClipChainUpTo(mClipChain, aASR);
-
-  if (mClipChain) {
-    mClip = &mClipChain->mClip;
-  } else {
-    mClip = nullptr;
-  }
-}
-
 void nsDisplayItem::IntersectClip(nsDisplayListBuilder* aBuilder,
                                   const DisplayItemClipChain* aOther,
                                   bool aStore) {

layout/painting/nsDisplayList.h

@@ -1045,14 +1045,6 @@ class nsDisplayListBuilder {
   const DisplayItemClipChain* CopyWholeChain(
       const DisplayItemClipChain* aClipChain);
 
-  /**
-   * Returns a new clip chain containing an intersection of all clips of
-   * |aClipChain| up to and including |aASR|.
-   * If there is no clip, returns nullptr.
-   */
-  const DisplayItemClipChain* FuseClipChainUpTo(
-      const DisplayItemClipChain* aClipChain, const ActiveScrolledRoot* aASR);
-
   const ActiveScrolledRoot* GetFilterASR() const { return mFilterASR; }
 
   /**
@@ -2867,13 +2859,6 @@ class nsDisplayItem : public nsDisplayItemLink {
                             bool aStore);
   const DisplayItemClipChain* GetClipChain() const { return mClipChain; }
 
-  /**
-   * Intersect all clips in our clip chain up to (and including) aASR and set
-   * set the intersection as this item's clip.
-   */
-  void FuseClipChainUpTo(nsDisplayListBuilder* aBuilder,
-                         const ActiveScrolledRoot* aASR);
-
   bool BackfaceIsHidden() const {
     return mItemFlags.contains(ItemFlag::BackfaceHidden);
   }