[css-display] Support display: contents pseudo-elements.

third_party/WebKit/Source/core/layout/LayoutObject.cpp

Index: third_party/WebKit/Source/core/layout/LayoutObject.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutObject.cpp b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
index 2fbf31901394b4a51cd540abc83dfd497dca7ab5..2164e68e01d9cb17e86b383a780deda261282715 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
@@ -35,6 +35,7 @@
 #include "core/css/resolver/StyleResolver.h"
 #include "core/dom/AXObjectCache.h"
 #include "core/dom/ElementTraversal.h"
+#include "core/dom/PseudoElement.h"
 #include "core/dom/StyleChangeReason.h"
 #include "core/dom/StyleEngine.h"
 #include "core/dom/shadow/ShadowRoot.h"
@@ -1588,6 +1589,11 @@ void LayoutObject::setPseudoStyle(PassRefPtr<ComputedStyle> pseudoStyle) {
   setStyle(std::move(pseudoStyle));
 }
 
+bool LayoutObject::isPseudoElementGeneratedContentFor(
+    const PseudoElement& pseudo) const {
+  return isAnonymous() && m_node.get() == &pseudo;
+}
+
 void LayoutObject::firstLineStyleDidChange(const ComputedStyle& oldStyle,
                                            const ComputedStyle& newStyle) {
   StyleDifference diff = oldStyle.visualInvalidationDiff(newStyle);