Add helper functions for list item and list element tags.

Added helper functions that check whether a given node has list or
list items tags. This is used in editing commands for list related
operations.

Bug: 942133
Change-Id: I950a0c8a5e0b87eeed091d68cebab921ddc55d67
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2527961
Auto-Submit: Anupam Snigdha <snianu@microsoft.com>
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825574}

third_party/blink/renderer/core/editing/commands/composite_edit_command.cc

@@ -1734,14 +1734,10 @@ bool CompositeEditCommand::BreakOutOfEmptyListItem(
   Node* next_list_node = empty_list_item->IsElementNode()
                              ? ElementTraversal::NextSibling(*empty_list_item)
                              : empty_list_item->nextSibling();
-  if (next_list_node && (list_node->HasTagName(html_names::kOlTag) ||
-                         list_node->HasTagName(html_names::kUlTag) ||
-                         list_node->HasTagName(html_names::kDlTag))) {
+  if (next_list_node && IsListElementTag(list_node)) {
     // If emptyListItem follows another list item or nested list, split the list
     // node.
-    if (previous_list_node->HasTagName(html_names::kLiTag) ||
-        previous_list_node->HasTagName(html_names::kDdTag) ||
-        previous_list_node->HasTagName(html_names::kDtTag) ||
+    if (IsListItemTag(previous_list_node) ||
         IsHTMLListElement(previous_list_node)) {
       SplitElement(To<Element>(list_node), empty_list_item);
     }

third_party/blink/renderer/core/editing/commands/editing_commands_utilities.cc

@@ -383,13 +383,7 @@ Node* EnclosingListChild(const Node* node) {
   // instead of node->parentNode()
   for (Node* n = const_cast<Node*>(node); n && n->parentNode();
        n = n->parentNode()) {
-    if (((n->HasTagName(html_names::kLiTag) ||
-          n->HasTagName(html_names::kDdTag) ||
-          n->HasTagName(html_names::kDtTag)) ||
-         (n->parentNode()->HasTagName(html_names::kUlTag) ||
-          n->parentNode()->HasTagName(html_names::kOlTag) ||
-          n->parentNode()->HasTagName(html_names::kDlTag))) &&
-        n != root) {
+    if ((IsListItemTag(n) || IsListElementTag(n->parentNode())) && n != root) {
       return n;
     }
     if (n == root || IsTableCell(n))

third_party/blink/renderer/core/editing/editing_utilities.cc

@@ -1132,6 +1132,18 @@ bool IsListItem(const Node* n) {
          n->GetLayoutObject()->IsListItemIncludingNG();
 }
 
+bool IsListItemTag(const Node* n) {
+  return n && (n->HasTagName(html_names::kLiTag) ||
+               n->HasTagName(html_names::kDdTag) ||
+               n->HasTagName(html_names::kDtTag));
+}
+
+bool IsListElementTag(const Node* n) {
+  return n && (n->HasTagName(html_names::kUlTag) ||
+               n->HasTagName(html_names::kOlTag) ||
+               n->HasTagName(html_names::kDlTag));
+}
+
 bool IsPresentationalHTMLElement(const Node* node) {
   const auto* element = DynamicTo<HTMLElement>(node);
   if (!element)

third_party/blink/renderer/core/editing/editing_utilities.h

@@ -166,6 +166,8 @@ bool IsDisplayInsideTable(const Node*);
 bool IsTableCell(const Node*);
 bool IsHTMLListElement(const Node*);
 bool IsListItem(const Node*);
+bool IsListItemTag(const Node*);
+bool IsListElementTag(const Node*);
 bool IsPresentationalHTMLElement(const Node*);
 bool IsRenderedAsNonInlineTableImageOrHR(const Node*);
 bool IsNonTableCellHTMLBlockElement(const Node*);