[css-pseudo] Simplify Marker() using PseudoElementLayoutObject()

Instead of using GetPseudoElement to obtain the ::marker pseudo-element
and then call GetLayoutObject on it, PseudoElementLayoutObject can
directly be used.

This patch should have no effect in practice.

BUG=457718

Change-Id: Iff30a916834b2e57e67be9ce145c2e992b224fd6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2078472Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Oriol Brufau <obrufau@igalia.com>
Cr-Commit-Position: refs/heads/master@{#745420}

third_party/blink/renderer/core/layout/layout_list_item.h

@@ -24,7 +24,6 @@
 #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_LAYOUT_LIST_ITEM_H_
 #define THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_LAYOUT_LIST_ITEM_H_
 
-#include "third_party/blink/renderer/core/dom/pseudo_element.h"
 #include "third_party/blink/renderer/core/html/list_item_ordinal.h"
 #include "third_party/blink/renderer/core/layout/layout_block_flow.h"
 #include "third_party/blink/renderer/core/layout/layout_list_marker.h"
@@ -43,12 +42,11 @@ class LayoutListItem final : public LayoutBlockFlow {
 
   LayoutListMarker* Marker() const {
     Element* list_item = To<Element>(GetNode());
-    if (PseudoElement* marker = list_item->GetPseudoElement(kPseudoIdMarker)) {
-      if (LayoutObject* layout_object = marker->GetLayoutObject()) {
-        if (layout_object->IsListMarker())
-          return ToLayoutListMarker(layout_object);
-        NOTREACHED();
-      }
+    if (LayoutObject* marker =
+            list_item->PseudoElementLayoutObject(kPseudoIdMarker)) {
+      if (marker->IsListMarker())
+        return ToLayoutListMarker(marker);
+      NOTREACHED();
     }
     return nullptr;
   }

third_party/blink/renderer/core/layout/ng/list/layout_ng_list_item.h

@@ -6,7 +6,6 @@
 #define THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_LIST_LAYOUT_NG_LIST_ITEM_H_
 
 #include "third_party/blink/renderer/core/core_export.h"
-#include "third_party/blink/renderer/core/dom/pseudo_element.h"
 #include "third_party/blink/renderer/core/html/list_item_ordinal.h"
 #include "third_party/blink/renderer/core/layout/ng/layout_ng_block_flow.h"
 
@@ -23,9 +22,7 @@ class CORE_EXPORT LayoutNGListItem final : public LayoutNGBlockFlow {
 
   LayoutObject* Marker() const {
     Element* list_item = To<Element>(GetNode());
-    if (PseudoElement* marker = list_item->GetPseudoElement(kPseudoIdMarker))
-      return marker->GetLayoutObject();
-    return nullptr;
+    return list_item->PseudoElementLayoutObject(kPseudoIdMarker);
   }
 
   void UpdateMarkerTextIfNeeded();