List marker pseudo elements.

Source/core/dom/LayoutTreeBuilder.cpp

Index: Source/core/dom/LayoutTreeBuilder.cpp
diff --git a/Source/core/dom/LayoutTreeBuilder.cpp b/Source/core/dom/LayoutTreeBuilder.cpp
index dd350812811ee8ebd7b0c38e49d254f11c2d25ab..61c925bd2a5c326f3dce7569bcc2ccb56cfc927c 100644
--- a/Source/core/dom/LayoutTreeBuilder.cpp
+++ b/Source/core/dom/LayoutTreeBuilder.cpp
@@ -31,6 +31,7 @@
 #include "core/css/resolver/StyleResolver.h"
 #include "core/dom/FirstLetterPseudoElement.h"
 #include "core/dom/Fullscreen.h"
+#include "core/dom/MarkerPseudoElement.h"
 #include "core/dom/Node.h"
 #include "core/dom/PseudoElement.h"
 #include "core/dom/Text.h"
@@ -67,6 +68,13 @@ LayoutObject* LayoutTreeBuilderForElement::nextLayoutObject() const
     if (m_node->isFirstLetterPseudoElement())
         return FirstLetterPseudoElement::firstLetterTextRenderer(*m_node);
 
+    if (m_node->isMarkerPseudoElement()) {
+        LayoutObject* parentLayoutObject = this->parentLayoutObject();
+        ASSERT(parentLayoutObject);
+
+        return MarkerPseudoElement::firstNonMarkerChild(parentLayoutObject);
+    }
+
     return LayoutTreeBuilder::nextLayoutObject();
 }
 
@@ -74,8 +82,13 @@ LayoutObject* LayoutTreeBuilderForElement::parentLayoutObject() const
 {
     LayoutObject* parentLayoutObject = LayoutTreeBuilder::parentLayoutObject();
 
+    if (m_node->isMarkerPseudoElement()) {
+        if (LayoutObject* markerLayoutObject = MarkerPseudoElement::parentOfFirstLineBox(m_layoutObjectParent, nullptr))
+            return markerLayoutObject;
+    }
+
     if (parentLayoutObject) {
-        // FIXME: Guarding this by parentLayoutObject isn't quite right as the spec for
+        // FIXME: Guarding this by parentRenderer isn't quite right as the spec for
         // top layer only talks about display: none ancestors so putting a <dialog> inside an
         // <optgroup> seems like it should still work even though this check will prevent it.
         if (m_node->isInTopLayer())
@@ -105,6 +118,9 @@ bool LayoutTreeBuilderForElement::shouldCreateLayoutObject() const
     if (!parentLayoutObject->canHaveChildren())
         return false;
 
+    if (m_node->isMarkerPseudoElement())
+        return true;
+
     return m_node->layoutObjectIsNeeded(style());
 }