Backed out changeset dc2ced1dd175 (bug 860524) for reftest failures

layout/base/DisplayItemClip.h

@@ -53,7 +53,15 @@ public:
   };
 
   // Constructs a DisplayItemClip that does no clipping at all.
-  DisplayItemClip() : mHaveClipRect(false) {}
+  DisplayItemClip() : mHaveClipRect(false), mHasBeenDestroyed(false) {}
+  ~DisplayItemClip() { mHasBeenDestroyed = true; }
+
+  void MaybeDestroy() const
+  {
+    if (!mHasBeenDestroyed) {
+      this->~DisplayItemClip();
+    }
+  }
 
   void SetTo(const nsRect& aRect);
   void SetTo(const nsRect& aRect, const nscoord* aRadii);
@@ -168,6 +176,9 @@ private:
   // If mHaveClipRect is false then this object represents no clipping at all
   // and mRoundedClipRects must be empty.
   bool mHaveClipRect;
+  // Set to true when the destructor has run. This is a bit of a hack
+  // to ensure that we can easily share arena-allocated DisplayItemClips.
+  bool mHasBeenDestroyed;
 };
 
 }

layout/base/DisplayListClipState.cpp

@@ -18,16 +18,17 @@ DisplayListClipState::GetCurrentCombinedClip(nsDisplayListBuilder* aBuilder)
   if (!mClipContentDescendants && !mClipContainingBlockDescendants) {
     return nullptr;
   }
+  void* mem = aBuilder->Allocate(sizeof(DisplayItemClip));
   if (mClipContentDescendants) {
     DisplayItemClip* newClip =
-      aBuilder->AllocateDisplayItemClip(*mClipContentDescendants);
+      new (mem) DisplayItemClip(*mClipContentDescendants);
     if (mClipContainingBlockDescendants) {
       newClip->IntersectWith(*mClipContainingBlockDescendants);
     }
     mCurrentCombinedClip = newClip;
   } else {
     mCurrentCombinedClip =
-      aBuilder->AllocateDisplayItemClip(*mClipContainingBlockDescendants);
+      new (mem) DisplayItemClip(*mClipContainingBlockDescendants);
   }
   return mCurrentCombinedClip;
 }

layout/base/nsDisplayList.cpp

@@ -707,10 +707,6 @@ nsDisplayListBuilder::~nsDisplayListBuilder() {
 
   nsCSSRendering::EndFrameTreesLocked();
 
-  for (uint32_t i = 0; i < mDisplayItemClipsToDestroy.Length(); ++i) {
-    mDisplayItemClipsToDestroy[i]->DisplayItemClip::~DisplayItemClip();
-  }
-
   PL_FinishArenaPool(&mPool);
   MOZ_COUNT_DTOR(nsDisplayListBuilder);
 }
@@ -872,15 +868,6 @@ nsDisplayListBuilder::Allocate(size_t aSize) {
   return tmp;
 }
 
-DisplayItemClip*
-nsDisplayListBuilder::AllocateDisplayItemClip(const DisplayItemClip& aOriginal)
-{
-  void* p = Allocate(sizeof(DisplayItemClip));
-  DisplayItemClip* c = new (p) DisplayItemClip(aOriginal);
-  mDisplayItemClipsToDestroy.AppendElement(c);
-  return c;
-}
-
 void nsDisplayListSet::MoveTo(const nsDisplayListSet& aDestination) const
 {
   aDestination.BorderBackground()->AppendToTop(BorderBackground());

layout/base/nsDisplayList.h

@@ -478,13 +478,7 @@ public:
    * destructors are called as soon as the item is no longer used.
    */
   void* Allocate(size_t aSize);
-
-  /**
-   * Allocate a new DisplayListClip in the arena. Will be cleaned up
-   * automatically when the arena goes away.
-   */
-  DisplayItemClip* AllocateDisplayItemClip(const DisplayItemClip& aOriginal);
-
+  
   /**
    * A helper class to temporarily set the value of
    * mIsAtRootOfPseudoStackingContext and mIsInFixedPosition, and temporarily
@@ -652,7 +646,6 @@ private:
   nsRegion                       mExcludedGlassRegion;
   // The display item for the Windows window glass background, if any
   nsDisplayItem*                 mGlassDisplayItem;
-  nsTArray<DisplayItemClip*>     mDisplayItemClipsToDestroy;
   Mode                           mMode;
   bool                           mBuildCaret;
   bool                           mIgnoreSuppression;
@@ -753,7 +746,12 @@ public:
 #endif
   {
   }
-  virtual ~nsDisplayItem() {}
+  virtual ~nsDisplayItem()
+  {
+    if (mClip) {
+      mClip->MaybeDestroy();
+    }
+  }
   
   void* operator new(size_t aSize,
                      nsDisplayListBuilder* aBuilder) CPP_THROW_NEW {
@@ -1195,11 +1193,17 @@ public:
   }
   void SetClip(nsDisplayListBuilder* aBuilder, const DisplayItemClip& aClip)
   {
+    if (mClip) {
+      mClip->MaybeDestroy();
+    }
     if (!aClip.HasClip()) {
       mClip = nullptr;
       return;
     }
-    mClip = aBuilder->AllocateDisplayItemClip(aClip);
+    void* mem = aBuilder->Allocate(sizeof(DisplayItemClip));
+    DisplayItemClip* clip = new (mem) DisplayItemClip();
+    *clip = aClip;
+    mClip = clip;
   }
 
 protected:

layout/reftests/border-radius/reftest.list

@@ -76,8 +76,6 @@ skip-if(B2G) random-if(winWidget) HTTP(..) == corner-joins-2.xhtml corner-joins-
 
 skip-if(B2G) fuzzy-if(/^Windows\x20NT\x206\.2/.test(http.oscpu),1,20) fuzzy-if(Android&&browserIsRemote,7,146) fuzzy-if(Android&&!browserIsRemote,166,248) == scroll-1.html scroll-1-ref.html # see bug 732535
 
-== transforms-1.html transforms-1-ref.html
-
 == zero-radius-clip-1.html zero-radius-clip-ref.html
 
 == iframe-1.html iframe-1-ref.html

layout/reftests/border-radius/transforms-1-ref.html

@@ -1,17 +0,0 @@
-<!DOCTYPE html>
-<html>
-<body style="background:white">
-<style>
-div {
-  position: absolute;
-  width: 100px;
-  height: 100px;
-  border: solid 2px black;
-  background: black;
-  border-radius: 30px;
-  overflow: hidden;
-}
-</style>
-<div>></div>
-</body>
-</html>

layout/reftests/border-radius/transforms-1.html

@@ -1,27 +0,0 @@
-<!DOCTYPE html>
-<html>
-<body style="background:white">
-<style>
-div {
-  position: absolute;
-  width: 100px;
-  height: 100px;
-  border: solid 2px black;
-  background: black;
-  border-radius: 30px;
-  overflow: hidden;
-}
-
-span {
-  position: absolute;
-  top: 0;
-  left: 0;
-  width: 100%;
-  height: 100%;
-  background: black;
-  transform: scale(2);
-}
-</style>
-<div><span></span></div>
-</body>
-</html>