List marker pseudo elements.

Source/core/dom/Element.cpp

Index: Source/core/dom/Element.cpp
diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
index ec3e3cab6ba4461399d2e34149e40d9f994f4e9b..3be6fd48abb5d1984fe989aacf138b89e322ec94 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -1463,6 +1463,11 @@ void Element::attach(const AttachContext& context)
     // from any of them.
     createPseudoElementIfNeeded(FIRST_LETTER);
 
+    // The marker has to come after the other content, including the BEFORE pseudo
+    // element so make sure we create it last.
+    if (RuntimeEnabledFeatures::listMarkerPseudoElementEnabled())
+        createPseudoElementIfNeeded(MARKER);
+
     if (hasRareData() && !renderer()) {
         if (ActiveAnimations* activeAnimations = elementRareData()->activeAnimations()) {
             activeAnimations->cssAnimations().cancel();
@@ -1626,6 +1631,8 @@ void Element::recalcStyle(StyleRecalcChange change, Text* nextTextSibling)
 
         updatePseudoElement(AFTER, change);
         updatePseudoElement(BACKDROP, change);
+        if (RuntimeEnabledFeatures::listMarkerPseudoElementEnabled())
+            updatePseudoElement(MARKER, change);
 
         // If our children have changed then we need to force the first-letter
         // checks as we don't know if they effected the first letter or not.
@@ -2632,7 +2639,8 @@ void Element::updatePseudoElement(PseudoId pseudoId, StyleRecalcChange change)
         // is false, otherwise we could continuously create and destroy PseudoElements
         // when RenderObject::isChildAllowed on our parent returns false for the
         // PseudoElement's renderer for each style recalc.
-        if (!renderer() || !pseudoElementRendererIsNeeded(renderer()->getCachedPseudoStyle(pseudoId)))
+        if (!renderer()
+            || (!pseudoElementRendererIsNeeded(renderer()->getCachedPseudoStyle(pseudoId)) && (pseudoId == MARKER && renderer()->style()->display() != LIST_ITEM)))
             elementRareData()->setPseudoElement(pseudoId, nullptr);
     } else if (pseudoId == FIRST_LETTER && element && change >= UpdatePseudoElements && !FirstLetterPseudoElement::firstLetterTextRenderer(*element)) {
         // This can happen if we change to a float, for example. We need to cleanup the
@@ -2667,7 +2675,7 @@ bool Element::updateFirstLetter(Element* element)
 
 void Element::createPseudoElementIfNeeded(PseudoId pseudoId)
 {
-    if (isPseudoElement())
+    if (isPseudoElement() && (pseudoId != MARKER || isMarkerPseudoElement()))
         return;
 
     // Document::ensureStyleResolver is not inlined and shows up on profiles, avoid it here.
@@ -2675,9 +2683,9 @@ void Element::createPseudoElementIfNeeded(PseudoId pseudoId)
     RefPtrWillBeRawPtr<PseudoElement> element = engine->ensureResolver().createPseudoElementIfNeeded(*this, pseudoId);
     if (!element)
         return;
-
     if (pseudoId == BACKDROP)
         document().addToTopLayer(element.get(), this);
+
     element->insertedInto(this);
     element->attach();