[LayoutNG] Implement hit testing on list marker

When hit testing a list marker, we should hit the corresponding list
item element. This patch implements the same behavior in LayoutNG.

Bug: 855279
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng;luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I4d191098a444cf276b917451ae1f9ab4a0df2d88
Reviewed-on: https://chromium-review.googlesource.com/1111270Reviewed-by: Koji Ishii <kojii@chromium.org>
Reviewed-by: cathie chen <cathiechen@tencent.com>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569735}

third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-features=LayoutNG

@@ -451,7 +451,6 @@ crbug.com/591099 fast/dynamic/text-combine.html [ Failure ]
 crbug.com/591099 fast/encoding/utf-16-big-endian.html [ Failure ]
 crbug.com/591099 fast/encoding/utf-16-little-endian.html [ Failure ]
 crbug.com/591099 fast/events/mouse-relative-position.html [ Failure ]
-crbug.com/591099 fast/events/onclick-list-marker.html [ Failure ]
 crbug.com/591099 fast/events/select-element.html [ Failure ]
 crbug.com/591099 fast/events/sequential-focus-navigation-starting-point.html [ Failure ]
 crbug.com/591099 fast/events/touch/compositor-touch-hit-rects.html [ Failure ]
@@ -874,7 +873,6 @@ crbug.com/591099 virtual/layout_ng/ [ Skip ]
 crbug.com/824918 virtual/layout_ng_experimental/ [ Skip ]
 crbug.com/591099 virtual/mojo-blob-urls/external/wpt/FileAPI/url/sandboxed-iframe.html [ Pass ]
 crbug.com/591099 virtual/mouseevent_fractional/fast/events/mouse-relative-position.html [ Failure ]
-crbug.com/591099 virtual/mouseevent_fractional/fast/events/onclick-list-marker.html [ Failure ]
 crbug.com/591099 virtual/mouseevent_fractional/fast/events/select-element.html [ Failure ]
 crbug.com/591099 virtual/mouseevent_fractional/fast/events/sequential-focus-navigation-starting-point.html [ Failure ]
 crbug.com/591099 virtual/mouseevent_fractional/fast/events/touch/compositor-touch-hit-rects.html [ Failure ]
@@ -897,7 +895,6 @@ crbug.com/591099 virtual/user-activation-v2/fast/dom/Window/window-lookup-preced
 crbug.com/591099 virtual/user-activation-v2/fast/events/event-on-culled_inline.html [ Failure Pass ]
 crbug.com/591099 virtual/user-activation-v2/fast/events/mouse-cursor.html [ Failure ]
 crbug.com/591099 virtual/user-activation-v2/fast/events/mouse-relative-position.html [ Failure ]
-crbug.com/591099 virtual/user-activation-v2/fast/events/onclick-list-marker.html [ Failure ]
 crbug.com/591099 virtual/user-activation-v2/fast/events/select-element.html [ Failure ]
 crbug.com/591099 virtual/user-activation-v2/fast/events/sequential-focus-navigation-starting-point.html [ Failure ]
 crbug.com/591099 virtual/user-activation-v2/fast/events/touch/compositor-touch-hit-rects.html [ Failure ]

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

@@ -40,10 +40,10 @@ class CORE_EXPORT LayoutNGListMarker final
 
   const char* GetName() const override { return "LayoutNGListMarker"; }
 
+  LayoutNGListItem* ListItem() const;
+
  private:
   bool IsOfType(LayoutObjectType) const override;
-
-  LayoutNGListItem* ListItem() const;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutNGListMarker, IsLayoutNGListMarker());

third_party/blink/renderer/core/paint/ng/ng_paint_fragment.cc

@@ -19,6 +19,8 @@
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_physical_line_box_fragment.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_physical_text_fragment.h"
 #include "third_party/blink/renderer/core/layout/ng/layout_ng_block_flow.h"
+#include "third_party/blink/renderer/core/layout/ng/list/layout_ng_list_item.h"
+#include "third_party/blink/renderer/core/layout/ng/list/layout_ng_list_marker.h"
 #include "third_party/blink/renderer/core/layout/ng/ng_fragment.h"
 #include "third_party/blink/renderer/core/layout/ng/ng_physical_box_fragment.h"
 #include "third_party/blink/renderer/core/layout/ng/ng_physical_container_fragment.h"
@@ -617,15 +619,25 @@ Node* NGPaintFragment::NodeForHitTest() const {
   if (PhysicalFragment().IsLineBox())
     return Parent()->NodeForHitTest();
 
-  // When the fragment is inside a ::first-letter, ::before or ::after pseudo
-  // node, return the pseudo node.
+  // When the fragment is a list marker, return the list item.
+  if (GetLayoutObject() && GetLayoutObject()->IsLayoutNGListMarker())
+    return ToLayoutNGListMarker(GetLayoutObject())->ListItem()->GetNode();
+
   for (const NGPaintFragment* runner = Parent(); runner;
        runner = runner->Parent()) {
+    // When the fragment is inside a ::first-letter, ::before or ::after pseudo
+    // node, return the pseudo node.
     if (Node* node = runner->GetNode()) {
       if (CanBeHitTestTargetPseudoNode(*node))
         return node;
       return nullptr;
     }
+
+    // When the fragment is inside a list marker, return the list item.
+    if (runner->GetLayoutObject() &&
+        runner->GetLayoutObject()->IsLayoutNGListMarker()) {
+      return runner->NodeForHitTest();
+    }
   }
 
   return nullptr;