Bug 1355351 - Make pseudo-elements return the correct style via getComputedStyle

* Add a node property to access the ::before and ::after pseudo-elements
* Look for the frame for ::before and ::after pseudos
* Clean up pseudo-element props
* Simplify nsLayoutUtils callers, and make child iterators notice display: contents pseudos

Tag #1375

7 files changed, 69 insertions, 72 deletions

diff --git a/dom/animation/EffectCompositor.cpp b/dom/animation/EffectCompositor.cpp
index c88cabe90b..49da3c0332 100644
--- a/dom/animation/EffectCompositor.cpp
+++ b/dom/animation/EffectCompositor.cpp
@@ -356,24 +356,16 @@ EffectCompositor::GetElementToRestyle(dom::Element* aElement,
     return aElement;
   }
 
-  nsIFrame* primaryFrame = aElement->GetPrimaryFrame();
-  if (!primaryFrame) {
-    return nullptr;
-  }
-  nsIFrame* pseudoFrame;
   if (aPseudoType == CSSPseudoElementType::before) {
-    pseudoFrame = nsLayoutUtils::GetBeforeFrame(primaryFrame);
-  } else if (aPseudoType == CSSPseudoElementType::after) {
-    pseudoFrame = nsLayoutUtils::GetAfterFrame(primaryFrame);
-  } else {
-    NS_NOTREACHED("Should not try to get the element to restyle for a pseudo "
-                  "other that :before or :after");
-    return nullptr;
+    return nsLayoutUtils::GetBeforePseudo(aElement);
   }
-  if (!pseudoFrame) {
-    return nullptr;
+  if (aPseudoType == CSSPseudoElementType::after) {
+    return nsLayoutUtils::GetAfterPseudo(aElement);
   }
-  return pseudoFrame->GetContent()->AsElement();
+
+  NS_NOTREACHED("Should not try to get the element to restyle for a pseudo "
+                "other that :before or :after");
+  return nullptr;
 }
 
 bool
diff --git a/dom/animation/KeyframeEffectReadOnly.cpp b/dom/animation/KeyframeEffectReadOnly.cpp
index 639e0b2b0d..164ee02925 100644
--- a/dom/animation/KeyframeEffectReadOnly.cpp
+++ b/dom/animation/KeyframeEffectReadOnly.cpp
@@ -1105,19 +1105,17 @@ KeyframeEffectReadOnly::GetAnimationFrame() const
     return nullptr;
   }
 
-  nsIFrame* frame = mTarget->mElement->GetPrimaryFrame();
-  if (!frame) {
-    return nullptr;
-  }
-
+  nsIFrame* frame;
   if (mTarget->mPseudoType == CSSPseudoElementType::before) {
-    frame = nsLayoutUtils::GetBeforeFrame(frame);
+    frame = nsLayoutUtils::GetBeforeFrame(mTarget->mElement);
   } else if (mTarget->mPseudoType == CSSPseudoElementType::after) {
-    frame = nsLayoutUtils::GetAfterFrame(frame);
+    frame = nsLayoutUtils::GetAfterFrame(mTarget->mElement);
   } else {
+    frame = mTarget->mElement->GetPrimaryFrame();
     MOZ_ASSERT(mTarget->mPseudoType == CSSPseudoElementType::NotPseudo,
                "unknown mTarget->mPseudoType");
   }
+
   if (!frame) {
     return nullptr;
   }
diff --git a/dom/base/ChildIterator.cpp b/dom/base/ChildIterator.cpp
index fb07e9a210..23b919516b 100644
--- a/dom/base/ChildIterator.cpp
+++ b/dom/base/ChildIterator.cpp
@@ -317,11 +317,9 @@ AllChildrenIterator::Get() const
 {
   switch (mPhase) {
     case eAtBeforeKid: {
-      nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
-      MOZ_ASSERT(frame, "No frame at eAtBeforeKid phase");
-      nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
-      MOZ_ASSERT(beforeFrame, "No content before frame at eAtBeforeKid phase");
-      return beforeFrame->GetContent();
+      Element* before = nsLayoutUtils::GetBeforePseudo(mOriginalContent);
+      MOZ_ASSERT(before, "No content before frame at eAtBeforeKid phase");
+      return before;
     }
 
     case eAtExplicitKids:
@@ -331,11 +329,9 @@ AllChildrenIterator::Get() const
       return mAnonKids[mAnonKidsIdx];
 
     case eAtAfterKid: {
-      nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
-      MOZ_ASSERT(frame, "No frame at eAtAfterKid phase");
-      nsIFrame* afterFrame = nsLayoutUtils::GetAfterFrame(frame);
-      MOZ_ASSERT(afterFrame, "No content before frame at eAtBeforeKid phase");
-      return afterFrame->GetContent();
+      Element* after = nsLayoutUtils::GetAfterPseudo(mOriginalContent);
+      MOZ_ASSERT(after, "No content after frame at eAtAfterKid phase");
+      return after;
     }
 
     default:
@@ -349,15 +345,10 @@ AllChildrenIterator::Seek(nsIContent* aChildToFind)
 {
   if (mPhase == eAtBegin || mPhase == eAtBeforeKid) {
     mPhase = eAtExplicitKids;
-    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
-    if (frame) {
-      nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
-      if (beforeFrame) {
-        if (beforeFrame->GetContent() == aChildToFind) {
-          mPhase = eAtBeforeKid;
-          return true;
-        }
-      }
+    Element* beforePseudo = nsLayoutUtils::GetBeforePseudo(mOriginalContent);
+    if (beforePseudo && beforePseudo == aChildToFind) {
+      mPhase = eAtBeforeKid;
+      return true;
     }
   }
 
@@ -404,13 +395,10 @@ AllChildrenIterator::GetNextChild()
 {
   if (mPhase == eAtBegin) {
     mPhase = eAtExplicitKids;
-    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
-    if (frame) {
-      nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
-      if (beforeFrame) {
-        mPhase = eAtBeforeKid;
-        return beforeFrame->GetContent();
-      }
+    Element* beforeContent = nsLayoutUtils::GetBeforePseudo(mOriginalContent);
+    if (beforeContent) {
+      mPhase = eAtBeforeKid;
+      return beforeContent;
     }
   }
 
@@ -446,13 +434,10 @@ AllChildrenIterator::GetNextChild()
       return mAnonKids[mAnonKidsIdx];
     }
 
-    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
-    if (frame) {
-      nsIFrame* afterFrame = nsLayoutUtils::GetAfterFrame(frame);
-      if (afterFrame) {
-        mPhase = eAtAfterKid;
-        return afterFrame->GetContent();
-      }
+    Element* afterContent = nsLayoutUtils::GetAfterPseudo(mOriginalContent);
+    if (afterContent) {
+      mPhase = eAtAfterKid;
+      return afterContent;
     }
   }
 
@@ -466,13 +451,10 @@ AllChildrenIterator::GetPreviousChild()
   if (mPhase == eAtEnd) {
     MOZ_ASSERT(mAnonKidsIdx == mAnonKids.Length());
     mPhase = eAtAnonKids;
-    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
-    if (frame) {
-      nsIFrame* afterFrame = nsLayoutUtils::GetAfterFrame(frame);
-      if (afterFrame) {
-        mPhase = eAtAfterKid;
-        return afterFrame->GetContent();
-      }
+    Element* afterContent = nsLayoutUtils::GetAfterPseudo(mOriginalContent);
+    if (afterContent) {
+      mPhase = eAtAfterKid;
+      return afterContent;
     }
   }
 
@@ -501,13 +483,10 @@ AllChildrenIterator::GetPreviousChild()
       return kid;
     }
 
-    nsIFrame* frame = mOriginalContent->GetPrimaryFrame();
-    if (frame) {
-      nsIFrame* beforeFrame = nsLayoutUtils::GetBeforeFrame(frame);
-      if (beforeFrame) {
-        mPhase = eAtBeforeKid;
-        return beforeFrame->GetContent();
-      }
+    Element* beforeContent = nsLayoutUtils::GetBeforePseudo(mOriginalContent);
+    if (beforeContent) {
+      mPhase = eAtBeforeKid;
+      return beforeContent;
     }
   }
 
diff --git a/dom/base/nsDOMWindowUtils.cpp b/dom/base/nsDOMWindowUtils.cpp
index 2ab5937ace..3f5b54c942 100644
--- a/dom/base/nsDOMWindowUtils.cpp
+++ b/dom/base/nsDOMWindowUtils.cpp
@@ -3657,11 +3657,11 @@ nsDOMWindowUtils::GetOMTAStyle(nsIDOMElement* aElement,
 
   RefPtr<nsROCSSPrimitiveValue> cssValue = nullptr;
   nsIFrame* frame = element->GetPrimaryFrame();
-  if (frame && !aPseudoElement.IsEmpty()) {
+  if (!aPseudoElement.IsEmpty()) {
     if (aPseudoElement.EqualsLiteral("::before")) {
-      frame = nsLayoutUtils::GetBeforeFrame(frame);
+      frame = nsLayoutUtils::GetBeforeFrame(element);
     } else if (aPseudoElement.EqualsLiteral("::after")) {
-      frame = nsLayoutUtils::GetAfterFrame(frame);
+      frame = nsLayoutUtils::GetAfterFrame(element);
     } else {
       return NS_ERROR_INVALID_ARG;
     }
diff --git a/dom/base/nsGkAtomList.h b/dom/base/nsGkAtomList.h
index c7c1197b1a..2f0e30387c 100644
--- a/dom/base/nsGkAtomList.h
+++ b/dom/base/nsGkAtomList.h
@@ -2144,12 +2144,14 @@ GK_ATOM(ongamepaddisconnected, "ongamepaddisconnected")
 #endif
 
 // Content property names
+GK_ATOM(afterPseudoProperty, "afterPseudoProperty")  // nsXMLElement*
 GK_ATOM(animationsProperty, "AnimationsProperty")        // FrameAnimations*
 GK_ATOM(animationsOfBeforeProperty, "AnimationsOfBeforeProperty") // FrameAnimations*
 GK_ATOM(animationsOfAfterProperty, "AnimationsOfAfterProperty") // FrameAnimations*
 GK_ATOM(animationEffectsProperty, "AnimationEffectsProperty") // EffectSet*
 GK_ATOM(animationEffectsForBeforeProperty, "AnimationsEffectsForBeforeProperty") // EffectSet*
 GK_ATOM(animationEffectsForAfterProperty, "AnimationsEffectsForAfterProperty") // EffectSet*
+GK_ATOM(beforePseudoProperty, "beforePseudoProperty")  // nsXMLElement*
 GK_ATOM(cssPseudoElementBeforeProperty, "CSSPseudoElementBeforeProperty") // CSSPseudoElement*
 GK_ATOM(cssPseudoElementAfterProperty, "CSSPseudoElementAfterProperty") // CSSPseudoElement*
 GK_ATOM(transitionsProperty, "TransitionsProperty")        // FrameTransitions*
diff --git a/dom/xml/nsXMLElement.cpp b/dom/xml/nsXMLElement.cpp
index 45163a1c42..ad0314f4ca 100644
--- a/dom/xml/nsXMLElement.cpp
+++ b/dom/xml/nsXMLElement.cpp
@@ -9,6 +9,7 @@
 #include "mozilla/dom/ElementInlines.h"
 #include "nsContentUtils.h" // nsAutoScriptBlocker
 
+using namespace mozilla;
 using namespace mozilla::dom;
 
 nsresult
@@ -29,4 +30,26 @@ nsXMLElement::WrapNode(JSContext *aCx, JS::Handle<JSObject*> aGivenProto)
   return ElementBinding::Wrap(aCx, this, aGivenProto);
 }
 
+void
+nsXMLElement::UnbindFromTree(bool aDeep, bool aNullParent)
+{
+  CSSPseudoElementType pseudoType = GetPseudoElementType();
+  bool isBefore = pseudoType == CSSPseudoElementType::before;
+  nsIAtom* property = isBefore
+    ? nsGkAtoms::beforePseudoProperty : nsGkAtoms::afterPseudoProperty;
+
+  switch (pseudoType) {
+    case CSSPseudoElementType::before:
+    case CSSPseudoElementType::after: {
+      MOZ_ASSERT(GetParent());
+      MOZ_ASSERT(GetParent()->IsElement());
+      GetParent()->DeleteProperty(property);
+      break;
+    }
+    default:
+      break;
+  }
+  Element::UnbindFromTree(aDeep, aNullParent);
+}
+
 NS_IMPL_ELEMENT_CLONE(nsXMLElement)
diff --git a/dom/xml/nsXMLElement.h b/dom/xml/nsXMLElement.h
index d16b82f399..85f79970cd 100644
--- a/dom/xml/nsXMLElement.h
+++ b/dom/xml/nsXMLElement.h
@@ -35,6 +35,9 @@ public:
 
   virtual nsIDOMNode* AsDOMNode() override { return this; }
 
+  virtual void UnbindFromTree(bool aDeep = true,
+                              bool aNullParent = true) override;
+
 protected:
   virtual ~nsXMLElement() {}