Make DocumentMarkerController::AddMarkerToNode() to take const Node&

This patch changes |DocumentMarkerController::AddMarkerToNode()| to take
|const Node&| instead of |const Node*| since it always non-null for improving
code health.

This patch is a follow-up of the patch[1].

[1] http://crrev.com/c/1050053 Make TextIterator::CurrentContainer() to return
const Node&.

Change-Id: I7041a969f730d07fcccaa8d745b6f2cb02ecbaab
Reviewed-on: https://chromium-review.googlesource.com/1051068
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Yoichi Osato <yoichio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557150}

third_party/blink/renderer/core/editing/markers/document_marker_controller.cc

@@ -273,17 +273,17 @@ void DocumentMarkerController::AddMarkerInternal(
 
     DocumentMarker* const new_marker = create_marker_from_offsets(
         start_offset_in_current_container, end_offset_in_current_container);
-    AddMarkerToNode(&node, new_marker);
+    AddMarkerToNode(node, new_marker);
   }
 }
 
-void DocumentMarkerController::AddMarkerToNode(const Node* node,
+void DocumentMarkerController::AddMarkerToNode(const Node& node,
                                                DocumentMarker* new_marker) {
   possibly_existing_marker_types_.Add(new_marker->GetType());
   SetContext(document_);
 
   Member<MarkerLists>& markers =
-      markers_.insert(node, nullptr).stored_value->value;
+      markers_.insert(&node, nullptr).stored_value->value;
   if (!markers) {
     markers = new MarkerLists;
     markers->Grow(DocumentMarker::kMarkerTypeIndexesCount);
@@ -296,7 +296,7 @@ void DocumentMarkerController::AddMarkerToNode(const Node* node,
   DocumentMarkerList* const list = ListForType(markers, new_marker_type);
   list->Add(new_marker);
 
-  InvalidatePaintForNode(*node);
+  InvalidatePaintForNode(node);
 }
 
 // Moves markers from src_node to dst_node. Markers are moved if their start

third_party/blink/renderer/core/editing/markers/document_marker_controller.h

@@ -143,7 +143,7 @@ class CORE_EXPORT DocumentMarkerController final
   void AddMarkerInternal(
       const EphemeralRange&,
       std::function<DocumentMarker*(int, int)> create_marker_from_offsets);
-  void AddMarkerToNode(const Node*, DocumentMarker*);
+  void AddMarkerToNode(const Node&, DocumentMarker*);
 
   using MarkerLists = HeapVector<Member<DocumentMarkerList>,
                                  DocumentMarker::kMarkerTypeIndexesCount>;