Bug 1368547 - Remove nsFrameManagerBase::mPlaceholderMap and instead store the placeholder on a frame property on the out-of-flow

Tag #1375

18 files changed, 52 insertions, 166 deletions

diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index bee9ed629..57410a55a 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -692,10 +692,9 @@ nsAbsoluteItems::nsAbsoluteItems(nsContainerFrame* aContainingBlock)
 void
 nsAbsoluteItems::AddChild(nsIFrame* aChild)
 {
-  NS_ASSERTION(aChild->PresContext()->FrameManager()->
-               GetPlaceholderFrameFor(aChild),
-               "Child without placeholder being added to nsAbsoluteItems?");
   aChild->AddStateBits(NS_FRAME_OUT_OF_FLOW);
+  NS_ASSERTION(aChild->GetPlaceholderFrame(),
+               "Child without placeholder being added to nsAbsoluteItems?");
   nsFrameItems::AddChild(aChild);
 }
 
@@ -3032,14 +3031,12 @@ nsCSSFrameConstructor::CreatePlaceholderFrameFor(nsIPresShell*     aPresShell,
 
   placeholderFrame->Init(aContent, aParentFrame, aPrevInFlow);
 
-  // The placeholder frame has a pointer back to the out-of-flow frame
+  // Associate the placeholder/out-of-flow with each other.
   placeholderFrame->SetOutOfFlowFrame(aFrame);
+  aFrame->SetProperty(nsIFrame::PlaceholderFrameProperty(), placeholderFrame);
 
   aFrame->AddStateBits(NS_FRAME_OUT_OF_FLOW);
 
-  // Add mapping from absolutely positioned frame to its placeholder frame
-  aPresShell->FrameManager()->RegisterPlaceholderFrame(placeholderFrame);
-
   return placeholderFrame;
 }
 
@@ -6702,7 +6699,7 @@ nsCSSFrameConstructor::FindFrameForContentSibling(nsIContent* aContent,
   // If the frame is out-of-flow, GetPrimaryFrame() will have returned the
   // out-of-flow frame; we want the placeholder.
   if (sibling->GetStateBits() & NS_FRAME_OUT_OF_FLOW) {
-    nsIFrame* placeholderFrame = GetPlaceholderFrameFor(sibling);
+    nsIFrame* placeholderFrame = sibling->GetPlaceholderFrame();
     NS_ASSERTION(placeholderFrame, "no placeholder for out-of-flow frame");
     sibling = placeholderFrame;
   }
@@ -7968,7 +7965,7 @@ nsCSSFrameConstructor::ContentRangeInserted(nsIContent*            aContainer,
         // the placeholder frame.
         if (insertion.mParentFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW) {
           nsPlaceholderFrame* placeholderFrame =
-            GetPlaceholderFrameFor(insertion.mParentFrame);
+            insertion.mParentFrame->GetPlaceholderFrame();
           NS_ASSERTION(placeholderFrame, "No placeholder for out-of-flow?");
           insertion.mParentFrame = placeholderFrame->GetParent();
         } else {
@@ -8456,7 +8453,7 @@ nsCSSFrameConstructor::ContentRemoved(nsIContent*  aContainer,
     // :first-letter style applies.
     nsIFrame* inflowChild = childFrame;
     if (childFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW) {
-      inflowChild = GetPlaceholderFrameFor(childFrame);
+      inflowChild = childFrame->GetPlaceholderFrame();
       NS_ASSERTION(inflowChild, "No placeholder for out-of-flow?");
     }
     nsContainerFrame* containingBlock =
@@ -8512,7 +8509,7 @@ nsCSSFrameConstructor::ContentRemoved(nsIContent*  aContainer,
 
     // Notify the parent frame that it should delete the frame
     if (childFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW) {
-      childFrame = GetPlaceholderFrameFor(childFrame);
+      childFrame = childFrame->GetPlaceholderFrame();
       NS_ASSERTION(childFrame, "Missing placeholder frame for out of flow.");
       parentFrame = childFrame->GetParent();
     }
@@ -9153,7 +9150,7 @@ nsCSSFrameConstructor::ReplicateFixedFrames(nsPageContentFrame* aParentFrame)
   // are within fixed frames, because that would cause duplicates on the new
   // page - bug 389619)
   for (nsIFrame* fixed = firstFixed; fixed; fixed = fixed->GetNextSibling()) {
-    nsIFrame* prevPlaceholder = GetPlaceholderFrameFor(fixed);
+    nsIFrame* prevPlaceholder = fixed->GetPlaceholderFrame();
     if (prevPlaceholder &&
         nsLayoutUtils::IsProperAncestorFrame(prevCanvasFrame, prevPlaceholder)) {
       // We want to use the same style as the primary style frame for
@@ -9417,7 +9414,7 @@ nsCSSFrameConstructor::MaybeRecreateContainerForFrameRemoval(nsIFrame* aFrame,
   // Now check for possibly needing to reconstruct due to a pseudo parent
   nsIFrame* inFlowFrame =
     (aFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW) ?
-      GetPlaceholderFrameFor(aFrame) : aFrame;
+      aFrame->GetPlaceholderFrame() : aFrame;
   MOZ_ASSERT(inFlowFrame, "How did that happen?");
   MOZ_ASSERT(inFlowFrame == inFlowFrame->FirstContinuation(),
              "placeholder for primary frame has previous continuations?");
@@ -11594,7 +11591,7 @@ nsCSSFrameConstructor::RemoveFloatingFirstLetterFrames(
   }
 
   // Discover the placeholder frame for the letter frame
-  nsPlaceholderFrame* placeholderFrame = GetPlaceholderFrameFor(floatFrame);
+  nsPlaceholderFrame* placeholderFrame = floatFrame->GetPlaceholderFrame();
   if (!placeholderFrame) {
     // Somethings really wrong
     return;
diff --git a/layout/base/nsFrameManager.cpp b/layout/base/nsFrameManager.cpp
index 83bcd61ec..d703537fa 100644
--- a/layout/base/nsFrameManager.cpp
+++ b/layout/base/nsFrameManager.cpp
@@ -46,34 +46,9 @@ using namespace mozilla::dom;
 
 //----------------------------------------------------------------------
 
-struct PlaceholderMapEntry : public PLDHashEntryHdr {
-  // key (the out of flow frame) can be obtained through placeholder frame
-  nsPlaceholderFrame *placeholderFrame;
-};
-
-static bool
-PlaceholderMapMatchEntry(const PLDHashEntryHdr *hdr, const void *key)
-{
-  const PlaceholderMapEntry *entry =
-    static_cast<const PlaceholderMapEntry*>(hdr);
-  NS_ASSERTION(entry->placeholderFrame->GetOutOfFlowFrame() !=
-               (void*)0xdddddddd,
-               "Dead placeholder in placeholder map");
-  return entry->placeholderFrame->GetOutOfFlowFrame() == key;
-}
-
-static const PLDHashTableOps PlaceholderMapOps = {
-  PLDHashTable::HashVoidPtrKeyStub,
-  PlaceholderMapMatchEntry,
-  PLDHashTable::MoveEntryStub,
-  PLDHashTable::ClearEntryStub,
-  nullptr
-};
-
 nsFrameManagerBase::nsFrameManagerBase()
   : mPresShell(nullptr)
   , mRootFrame(nullptr)
-  , mPlaceholderMap(&PlaceholderMapOps, sizeof(PlaceholderMapEntry))
   , mUndisplayedMap(nullptr)
   , mDisplayContentsMap(nullptr)
   , mIsDestroyingFrames(false)
@@ -142,9 +117,6 @@ nsFrameManager::Destroy()
   // Destroy the frame hierarchy.
   mPresShell->SetIgnoreFrameDestruction(true);
 
-  // Unregister all placeholders before tearing down the frame tree
-  nsFrameManager::ClearPlaceholderFrameMap();
-
   if (mRootFrame) {
     mRootFrame->Destroy();
     mRootFrame = nullptr;
@@ -159,56 +131,6 @@ nsFrameManager::Destroy()
 
 //----------------------------------------------------------------------
 
-// Placeholder frame functions
-nsPlaceholderFrame*
-nsFrameManager::GetPlaceholderFrameFor(const nsIFrame* aFrame)
-{
-  NS_PRECONDITION(aFrame, "null param unexpected");
-
-  auto entry = static_cast<PlaceholderMapEntry*>
-    (const_cast<PLDHashTable*>(&mPlaceholderMap)->Search(aFrame));
-  if (entry) {
-    return entry->placeholderFrame;
-  }
-
-  return nullptr;
-}
-
-void
-nsFrameManager::RegisterPlaceholderFrame(nsPlaceholderFrame* aPlaceholderFrame)
-{
-  MOZ_ASSERT(aPlaceholderFrame, "null param unexpected");
-  MOZ_ASSERT(nsGkAtoms::placeholderFrame == aPlaceholderFrame->GetType(),
-             "unexpected frame type");
-  auto entry = static_cast<PlaceholderMapEntry*>
-    (mPlaceholderMap.Add(aPlaceholderFrame->GetOutOfFlowFrame()));
-  MOZ_ASSERT(!entry->placeholderFrame,
-             "Registering a placeholder for a frame that already has a placeholder!");
-  entry->placeholderFrame = aPlaceholderFrame;
-}
-
-void
-nsFrameManager::UnregisterPlaceholderFrame(nsPlaceholderFrame* aPlaceholderFrame)
-{
-  NS_PRECONDITION(aPlaceholderFrame, "null param unexpected");
-  NS_PRECONDITION(nsGkAtoms::placeholderFrame == aPlaceholderFrame->GetType(),
-                  "unexpected frame type");
-
-  mPlaceholderMap.Remove(aPlaceholderFrame->GetOutOfFlowFrame());
-}
-
-void
-nsFrameManager::ClearPlaceholderFrameMap()
-{
-  for (auto iter = mPlaceholderMap.Iter(); !iter.Done(); iter.Next()) {
-    auto entry = static_cast<PlaceholderMapEntry*>(iter.Get());
-    entry->placeholderFrame->SetOutOfFlowFrame(nullptr);
-  }
-  mPlaceholderMap.Clear();
-}
-
-//----------------------------------------------------------------------
-
 /* static */ nsStyleContext*
 nsFrameManager::GetStyleContextInMap(UndisplayedMap* aMap, nsIContent* aContent)
 {
@@ -497,7 +419,7 @@ nsFrameManager::RemoveFrame(ChildListID     aListID,
                aOldFrame->GetType() == nsGkAtoms::textFrame,
                "Must remove first continuation.");
   NS_ASSERTION(!(aOldFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW &&
-                 GetPlaceholderFrameFor(aOldFrame)),
+                 aOldFrame->GetPlaceholderFrame()),
                "Must call RemoveFrame on placeholder for out-of-flows.");
   nsContainerFrame* parentFrame = aOldFrame->GetParent();
   if (parentFrame->IsAbsoluteContainer() &&
diff --git a/layout/base/nsFrameManager.h b/layout/base/nsFrameManager.h
index bca4a581a..84d2c93e7 100644
--- a/layout/base/nsFrameManager.h
+++ b/layout/base/nsFrameManager.h
@@ -51,9 +51,7 @@ struct UndisplayedNode : public LinkedListElement<UndisplayedNode>
 } // namespace mozilla
 
 /**
- * Frame manager interface. The frame manager serves two purposes:
- * <li>provides a service for mapping from content to frame and from
- * out-of-flow frame to placeholder frame.
+ * Frame manager interface. The frame manager serves one purpose:
  * <li>handles structural modifications to the frame model. If the frame model
  * lock can be acquired, then the changes are processed immediately; otherwise,
  * they're queued and processed later.
@@ -81,13 +79,6 @@ public:
    */
   void Destroy();
 
-  // Placeholder frame functions
-  nsPlaceholderFrame* GetPlaceholderFrameFor(const nsIFrame* aFrame);
-  void RegisterPlaceholderFrame(nsPlaceholderFrame* aPlaceholderFrame);
-  void UnregisterPlaceholderFrame(nsPlaceholderFrame* aPlaceholderFrame);
-
-  void      ClearPlaceholderFrameMap();
-
   // Mapping undisplayed content
   nsStyleContext* GetUndisplayedContent(nsIContent* aContent)
   {
diff --git a/layout/base/nsFrameManagerBase.h b/layout/base/nsFrameManagerBase.h
index 757dce7e5..bb192b64f 100644
--- a/layout/base/nsFrameManagerBase.h
+++ b/layout/base/nsFrameManagerBase.h
@@ -53,7 +53,6 @@ protected:
   // weak link, because the pres shell owns us
   nsIPresShell* MOZ_NON_OWNING_REF mPresShell;
   nsIFrame*                       mRootFrame;
-  PLDHashTable                    mPlaceholderMap;
   UndisplayedMap*                 mUndisplayedMap;
   UndisplayedMap*                 mDisplayContentsMap;
   bool                            mIsDestroyingFrames;  // The frame manager is destroying some frame(s).
diff --git a/layout/base/nsFrameTraversal.cpp b/layout/base/nsFrameTraversal.cpp
index 9ea6349f4..76dd40af1 100644
--- a/layout/base/nsFrameTraversal.cpp
+++ b/layout/base/nsFrameTraversal.cpp
@@ -493,8 +493,7 @@ nsFrameIterator::GetPlaceholderFrame(nsIFrame* aFrame)
   if (MOZ_LIKELY(!aFrame || !aFrame->HasAnyStateBits(NS_FRAME_OUT_OF_FLOW))) {
     return aFrame;
   }
-  nsIFrame* placeholder =
-    aFrame->PresContext()->PresShell()->GetPlaceholderFrameFor(aFrame);
+  nsIFrame* placeholder = aFrame->GetPlaceholderFrame();
   return placeholder ? placeholder : aFrame;
 }
 
diff --git a/layout/base/nsIPresShell.h b/layout/base/nsIPresShell.h
index f89639b3e..0a5f9e6e7 100644
--- a/layout/base/nsIPresShell.h
+++ b/layout/base/nsIPresShell.h
@@ -486,12 +486,6 @@ public:
   virtual nsCanvasFrame* GetCanvasFrame() const = 0;
 
   /**
-   * Gets the placeholder frame associated with the specified frame. This is
-   * a helper frame that forwards the request to the frame manager.
-   */
-  virtual nsIFrame* GetPlaceholderFrameFor(nsIFrame* aFrame) const = 0;
-
-  /**
    * Tell the pres shell that a frame needs to be marked dirty and needs
    * Reflow.  It's OK if this is an ancestor of the frame needing reflow as
    * long as the ancestor chain between them doesn't cross a reflow root.
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index de3482246..2c4449994 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -4348,8 +4348,7 @@ nsLayoutUtils::GetParentOrPlaceholderFor(nsIFrame* aFrame)
 {
   if ((aFrame->GetStateBits() & NS_FRAME_OUT_OF_FLOW)
       && !aFrame->GetPrevInFlow()) {
-    return aFrame->PresContext()->PresShell()->FrameManager()->
-      GetPlaceholderFrameFor(aFrame);
+    return aFrame->GetProperty(nsIFrame::PlaceholderFrameProperty());
   }
   return aFrame->GetParent();
 }
diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index b190622c7..2407db650 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -4596,12 +4596,6 @@ PresShell::StyleRuleRemoved(StyleSheet* aStyleSheet)
   RecordStyleSheetChange(aStyleSheet);
 }
 
-nsIFrame*
-PresShell::GetPlaceholderFrameFor(nsIFrame* aFrame) const
-{
-  return mFrameConstructor->GetPlaceholderFrameFor(aFrame);
-}
-
 nsresult
 PresShell::RenderDocument(const nsRect& aRect, uint32_t aFlags,
                           nscolor aBackgroundColor,
diff --git a/layout/base/nsPresShell.h b/layout/base/nsPresShell.h
index f276273fa..c25d07e66 100644
--- a/layout/base/nsPresShell.h
+++ b/layout/base/nsPresShell.h
@@ -130,7 +130,6 @@ public:
   virtual nsIPageSequenceFrame* GetPageSequenceFrame() const override;
   virtual nsCanvasFrame* GetCanvasFrame() const override;
 
-  virtual nsIFrame* GetPlaceholderFrameFor(nsIFrame* aFrame) const override;
   virtual void FrameNeedsReflow(nsIFrame *aFrame, IntrinsicDirty aIntrinsicDirty,
                                 nsFrameState aBitToAdd,
                                 ReflowRootHandling aRootHandling =
diff --git a/layout/generic/ReflowInput.cpp b/layout/generic/ReflowInput.cpp
index 78eca8c6c..9f7b4368c 100644
--- a/layout/generic/ReflowInput.cpp
+++ b/layout/generic/ReflowInput.cpp
@@ -1564,8 +1564,7 @@ ReflowInput::InitAbsoluteConstraints(nsPresContext* aPresContext,
   // have been if it had been in the flow
   nsHypotheticalPosition hypotheticalPos;
   if ((iStartIsAuto && iEndIsAuto) || (bStartIsAuto && bEndIsAuto)) {
-    nsIFrame* placeholderFrame =
-      aPresContext->PresShell()->GetPlaceholderFrameFor(mFrame);
+    nsPlaceholderFrame* placeholderFrame = mFrame->GetPlaceholderFrame();
     NS_ASSERTION(placeholderFrame, "no placeholder frame");
 
     if (placeholderFrame->HasAnyStateBits(
diff --git a/layout/generic/nsAbsoluteContainingBlock.cpp b/layout/generic/nsAbsoluteContainingBlock.cpp
index e3c847d01..a92a2062d 100644
--- a/layout/generic/nsAbsoluteContainingBlock.cpp
+++ b/layout/generic/nsAbsoluteContainingBlock.cpp
@@ -338,17 +338,9 @@ nsAbsoluteContainingBlock::DoMarkFramesDirty(bool aMarkAllDirty)
 // Given an out-of-flow frame, this method returns the parent frame of
 // its placeholder frame, if that parent is a nsContainerFrame.
 static nsContainerFrame*
-GetPlaceholderContainer(nsPresContext* aPresContext,
-                        nsIFrame* aPositionedFrame)
+GetPlaceholderContainer(nsIFrame* aPositionedFrame)
 {
-  MOZ_ASSERT(aPositionedFrame, "need non-null frame");
-  MOZ_ASSERT(aPositionedFrame->HasAnyStateBits(NS_FRAME_OUT_OF_FLOW),
-             "expecting abspos frame");
-  MOZ_ASSERT(aPresContext && aPresContext == aPositionedFrame->PresContext(),
-             "need non-null pres context which matches our frame");
-
-  nsIFrame* placeholder =
-    aPresContext->PresShell()->GetPlaceholderFrameFor(aPositionedFrame);
+  nsIFrame* placeholder = aPositionedFrame->GetPlaceholderFrame();
 
   if (!placeholder) {
     return nullptr;
@@ -557,8 +549,7 @@ nsAbsoluteContainingBlock::ResolveSizeDependentOffsets(
         aOffsets->IEnd(outerWM) - aMargin.IStartEnd(outerWM) -
         aKidSize.ISize(outerWM);
     } else if (aKidReflowInput.mFlags.mIOffsetsNeedCSSAlign) {
-      placeholderContainer = GetPlaceholderContainer(aPresContext,
-                                                     aKidReflowInput.mFrame);
+      placeholderContainer = GetPlaceholderContainer(aKidReflowInput.mFrame);
       nscoord offset = OffsetToAlignedStaticPos(aKidReflowInput, aKidSize,
                                                 logicalCBSizeOuterWM,
                                                 placeholderContainer,
@@ -579,8 +570,7 @@ nsAbsoluteContainingBlock::ResolveSizeDependentOffsets(
         aKidSize.BSize(outerWM);
     } else if (aKidReflowInput.mFlags.mBOffsetsNeedCSSAlign) {
       if (!placeholderContainer) {
-        placeholderContainer = GetPlaceholderContainer(aPresContext,
-                                                       aKidReflowInput.mFrame);
+        placeholderContainer = GetPlaceholderContainer(aKidReflowInput.mFrame);
       }
       nscoord offset = OffsetToAlignedStaticPos(aKidReflowInput, aKidSize,
                                                 logicalCBSizeOuterWM,
@@ -655,8 +645,7 @@ nsAbsoluteContainingBlock::ReflowAbsoluteFrame(nsIFrame*                aDelegat
     // due to the multiple coordinate spaces in play, we use a convenience flag
     // to simply have the child's ReflowInput give it a static position at its
     // abs.pos. CB origin, and then we'll align & offset it from there.
-    nsIFrame* placeholder =
-      aPresContext->PresShell()->GetPlaceholderFrameFor(aKidFrame);
+    nsIFrame* placeholder = aKidFrame->GetPlaceholderFrame();
     if (placeholder && placeholder->GetParent() == aDelegatingFrame) {
       rsFlags |= ReflowInput::STATIC_POS_IS_CB_ORIGIN;
     }
diff --git a/layout/generic/nsBlockFrame.cpp b/layout/generic/nsBlockFrame.cpp
index a37bfc06b..8fec6cd6a 100644
--- a/layout/generic/nsBlockFrame.cpp
+++ b/layout/generic/nsBlockFrame.cpp
@@ -4336,8 +4336,7 @@ CheckPlaceholderInLine(nsIFrame* aBlock, nsLineBox* aLine, nsFloatCache* aFC)
                "float in a line should never be a continuation");
   NS_ASSERTION(!(aFC->mFloat->GetStateBits() & NS_FRAME_IS_PUSHED_FLOAT),
                "float in a line should never be a pushed float");
-  nsIFrame* ph = aBlock->PresContext()->FrameManager()->
-                   GetPlaceholderFrameFor(aFC->mFloat->FirstInFlow());
+  nsIFrame* ph = aFC->mFloat->FirstInFlow()->GetPlaceholderFrame();
   for (nsIFrame* f = ph; f; f = f->GetParent()) {
     if (f->GetParent() == aBlock)
       return aLine->Contains(f);
@@ -4939,9 +4938,8 @@ nsBlockFrame::DrainSelfPushedFloats()
       if (f->GetPrevContinuation()) {
         // FIXME
       } else {
-        nsPlaceholderFrame *placeholder =
-          presContext->FrameManager()->GetPlaceholderFrameFor(f);
-        nsIFrame *floatOriginalParent = presContext->PresShell()->
+        nsPlaceholderFrame* placeholder = f->GetPlaceholderFrame();
+        nsIFrame* floatOriginalParent = presContext->PresShell()->
           FrameConstructor()->GetFloatContainingBlock(placeholder);
         if (floatOriginalParent != this) {
           // This is a first continuation that was pushed from one of our
@@ -5565,7 +5563,7 @@ FindChildContaining(nsBlockFrame* aFrame, nsIFrame* aFindFrame)
       return nullptr;
     if (!(child->GetStateBits() & NS_FRAME_OUT_OF_FLOW))
       break;
-    aFindFrame = aFrame->PresContext()->FrameManager()->GetPlaceholderFrameFor(child);
+    aFindFrame = child->GetPlaceholderFrame();
   }
 
   return child;
@@ -6847,9 +6845,8 @@ nsBlockFrame::ChildIsDirty(nsIFrame* aChild)
       AddStateBits(NS_BLOCK_LOOK_FOR_DIRTY_FRAMES);
     } else {
       NS_ASSERTION(aChild->IsFloating(), "should be a float");
-      nsIFrame *thisFC = FirstContinuation();
-      nsIFrame *placeholderPath =
-        PresContext()->FrameManager()->GetPlaceholderFrameFor(aChild);
+      nsIFrame* thisFC = FirstContinuation();
+      nsIFrame* placeholderPath = aChild->GetPlaceholderFrame();
       // SVG code sometimes sends FrameNeedsReflow notifications during
       // frame destruction, leading to null placeholders, but we're safe
       // ignoring those.
diff --git a/layout/generic/nsFirstLetterFrame.cpp b/layout/generic/nsFirstLetterFrame.cpp
index 980e1e9be..5f561c759 100644
--- a/layout/generic/nsFirstLetterFrame.cpp
+++ b/layout/generic/nsFirstLetterFrame.cpp
@@ -320,8 +320,7 @@ nsFirstLetterFrame::CreateContinuationForFloatingParent(nsPresContext* aPresCont
   *aContinuation = nullptr;
 
   nsIPresShell* presShell = aPresContext->PresShell();
-  nsPlaceholderFrame* placeholderFrame =
-    presShell->FrameManager()->GetPlaceholderFrameFor(this);
+  nsPlaceholderFrame* placeholderFrame = GetPlaceholderFrame();
   nsContainerFrame* parent = placeholderFrame->GetParent();
 
   nsIFrame* continuation = presShell->FrameConstructor()->
diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index 25b685fb2..ea29c6945 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -633,8 +633,7 @@ nsFrame::DestroyFrom(nsIFrame* aDestructRoot)
 
   nsIPresShell *shell = presContext->GetPresShell();
   if (mState & NS_FRAME_OUT_OF_FLOW) {
-    nsPlaceholderFrame* placeholder =
-      shell->FrameManager()->GetPlaceholderFrameFor(this);
+    nsPlaceholderFrame* placeholder = GetPlaceholderFrame();
     NS_ASSERTION(!placeholder || (aDestructRoot != this),
                  "Don't call Destroy() on OOFs, call Destroy() on the placeholder.");
     NS_ASSERTION(!placeholder ||
@@ -642,7 +641,6 @@ nsFrame::DestroyFrom(nsIFrame* aDestructRoot)
                  "Placeholder relationship should have been torn down already; "
                  "this might mean we have a stray placeholder in the tree.");
     if (placeholder) {
-      shell->FrameManager()->UnregisterPlaceholderFrame(placeholder);
       placeholder->SetOutOfFlowFrame(nullptr);
     }
   }
@@ -8073,9 +8071,8 @@ int32_t
 nsFrame::GetLineNumber(nsIFrame *aFrame, bool aLockScroll, nsIFrame** aContainingBlock)
 {
   NS_ASSERTION(aFrame, "null aFrame");
-  nsFrameManager* frameManager = aFrame->PresContext()->FrameManager();
-  nsIFrame *blockFrame = aFrame;
-  nsIFrame *thisBlock;
+  nsIFrame* blockFrame = aFrame;
+  nsIFrame* thisBlock;
   nsAutoLineIterator it;
   nsresult result = NS_ERROR_FAILURE;
   while (NS_FAILED(result) && blockFrame)
@@ -8088,7 +8085,7 @@ nsFrame::GetLineNumber(nsIFrame *aFrame, bool aLockScroll, nsIFrame** aContainin
         // abspos continuations don't have placeholders, get the fif
         thisBlock = thisBlock->FirstInFlow();
       }
-      thisBlock = frameManager->GetPlaceholderFrameFor(thisBlock);
+      thisBlock = thisBlock->GetPlaceholderFrame();
       if (!thisBlock)
         return -1;
     }  
@@ -9040,7 +9037,6 @@ nsStyleContext*
 nsFrame::DoGetParentStyleContext(nsIFrame** aProviderFrame) const
 {
   *aProviderFrame = nullptr;
-  nsFrameManager* fm = PresContext()->FrameManager();
 
   // Handle display:contents and the root frame, when there's no parent frame
   // to inherit from.
@@ -9057,6 +9053,7 @@ nsFrame::DoGetParentStyleContext(nsIFrame** aProviderFrame) const
           /* if next is true then it's really a request for the table frame's
              parent context, see nsTable[Outer]Frame::GetParentStyleContext. */
           pseudo == nsCSSAnonBoxes::tableWrapper) {
+        nsFrameManager* fm = PresContext()->FrameManager();
         nsStyleContext* sc = fm->GetDisplayContentsStyleFor(parentContent);
         if (MOZ_UNLIKELY(sc)) {
           return sc;
@@ -9093,7 +9090,7 @@ nsFrame::DoGetParentStyleContext(nsIFrame** aProviderFrame) const
   // We're an out-of-flow frame.  For out-of-flow frames, we must
   // resolve underneath the placeholder's parent.  The placeholder is
   // reached from the first-in-flow.
-  nsIFrame* placeholder = fm->GetPlaceholderFrameFor(FirstInFlow());
+  nsIFrame* placeholder = FirstInFlow()->GetPlaceholderFrame();
   if (!placeholder) {
     NS_NOTREACHED("no placeholder frame for out-of-flow frame");
     *aProviderFrame = GetCorrectedParent(this);
diff --git a/layout/generic/nsIFrame.h b/layout/generic/nsIFrame.h
index 9372b15a2..e22dd690a 100644
--- a/layout/generic/nsIFrame.h
+++ b/layout/generic/nsIFrame.h
@@ -82,6 +82,7 @@ class nsLineList_iterator;
 class nsAbsoluteContainingBlock;
 class nsIContent;
 class nsContainerFrame;
+class nsPlaceholderFrame;
 
 struct nsPeekOffsetStruct;
 struct nsPoint;
@@ -729,6 +730,16 @@ public:
   inline nsContainerFrame* GetInFlowParent();
 
   /**
+   * Return the placeholder for this frame (which must be out-of-flow).
+   * @note this will only return non-null if |this| is the first-in-flow
+   * although we don't assert that here for legacy reasons.
+   */
+  inline nsPlaceholderFrame* GetPlaceholderFrame() const {
+    MOZ_ASSERT(HasAnyStateBits(NS_FRAME_OUT_OF_FLOW));
+    return GetProperty(PlaceholderFrameProperty());
+  }
+
+  /**
    * Set this frame's parent to aParent.
    * If the frame may have moved into or out of a scrollframe's
    * frame subtree, StickyScrollContainer::NotifyReparentedFrameAcrossScrollFrameBoundary
@@ -1047,6 +1058,8 @@ public:
 
   NS_DECLARE_FRAME_PROPERTY_SMALL_VALUE(BidiDataProperty, mozilla::FrameBidiData)
 
+  NS_DECLARE_FRAME_PROPERTY_WITHOUT_DTOR(PlaceholderFrameProperty, nsPlaceholderFrame)
+
   mozilla::FrameBidiData GetBidiData()
   {
     return GetProperty(BidiDataProperty());
diff --git a/layout/generic/nsIFrameInlines.h b/layout/generic/nsIFrameInlines.h
index 3068c9f79..a3da7ebca 100644
--- a/layout/generic/nsIFrameInlines.h
+++ b/layout/generic/nsIFrameInlines.h
@@ -166,8 +166,8 @@ nsContainerFrame*
 nsIFrame::GetInFlowParent()
 {
   if (GetStateBits() & NS_FRAME_OUT_OF_FLOW) {
-    nsFrameManager* fm = PresContext()->FrameManager();
-    return fm->GetPlaceholderFrameFor(FirstContinuation())->GetParent();
+    nsIFrame* ph = FirstContinuation()->GetProperty(nsIFrame::PlaceholderFrameProperty());
+    return ph->GetParent();
   }
 
   return GetParent();
diff --git a/layout/generic/nsPlaceholderFrame.cpp b/layout/generic/nsPlaceholderFrame.cpp
index bd380a2d9..62370a06a 100644
--- a/layout/generic/nsPlaceholderFrame.cpp
+++ b/layout/generic/nsPlaceholderFrame.cpp
@@ -156,16 +156,15 @@ nsPlaceholderFrame::DestroyFrom(nsIFrame* aDestructRoot)
 {
   nsIFrame* oof = mOutOfFlowFrame;
   if (oof) {
-    // Unregister out-of-flow frame
-    nsFrameManager* fm = PresContext()->GetPresShell()->FrameManager();
-    fm->UnregisterPlaceholderFrame(this);
     mOutOfFlowFrame = nullptr;
+    oof->DeleteProperty(nsIFrame::PlaceholderFrameProperty());
     // If aDestructRoot is not an ancestor of the out-of-flow frame,
     // then call RemoveFrame on it here.
     // Also destroy it here if it's a popup frame. (Bug 96291)
     if ((GetStateBits() & PLACEHOLDER_FOR_POPUP) ||
         !nsLayoutUtils::IsProperAncestorFrame(aDestructRoot, oof)) {
       ChildListID listId = nsLayoutUtils::GetChildListNameFor(oof);
+      nsFrameManager* fm = PresContext()->GetPresShell()->FrameManager();
       fm->RemoveFrame(listId, oof);
     }
     // else oof will be destroyed by its parent
diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
index 59ef020ce..6875f33e8 100644
--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -1383,8 +1383,7 @@ BuildTextRuns(DrawTarget* aDrawTarget, nsTextFrame* aForFrame,
   nsIFrame* lineContainerChild = aForFrame;
   if (!aLineContainer) {
     if (aForFrame->IsFloatingFirstLetterChild()) {
-      lineContainerChild = aForFrame->PresContext()->PresShell()->
-        GetPlaceholderFrameFor(aForFrame->GetParent());
+      lineContainerChild = aForFrame->GetParent()->GetPlaceholderFrame();
     }
     aLineContainer = FindLineContainer(lineContainerChild);
   } else {