Replace |PositionForPoint| with |GetPosition|

This patch replaces two usages of |LayoutObject::PositionForPoint|
with |HitTestResult::GetPosition| because the former does not
support NG block fragmentation.

There are some minor differences in the behavior. But
according to yosin@, using |InnerPossiblyPseudoNode| instead
of |InnerNode| is most likely more correct.

Bug: 829028
Change-Id: I6fda4161f60e2cafb78c12370484bf464331a5f4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2535530
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827152}

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

@@ -628,13 +628,8 @@ bool FrameSelection::Contains(const PhysicalOffset& point) {
   HitTestLocation location(point);
   HitTestResult result(request, location);
   GetDocument().GetLayoutView()->HitTest(location, result);
-  Node* inner_node = result.InnerNode();
-  if (!inner_node || !inner_node->GetLayoutObject())
-    return false;
-
   const PositionInFlatTreeWithAffinity pos_with_affinity =
-      FromPositionInDOMTree<EditingInFlatTreeStrategy>(
-          inner_node->GetLayoutObject()->PositionForPoint(result.LocalPoint()));
+      FromPositionInDOMTree<EditingInFlatTreeStrategy>(result.GetPosition());
   if (pos_with_affinity.IsNull())
     return false;
 

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

@@ -1193,11 +1193,7 @@ void SelectionController::HandleGestureTwoFingerTap(
 }
 
 static bool HitTestResultIsMisspelled(const HitTestResult& result) {
-  Node* inner_node = result.InnerPossiblyPseudoNode();
-  if (!inner_node || !inner_node->GetLayoutObject())
-    return false;
-  PositionWithAffinity pos_with_affinity =
-      inner_node->GetLayoutObject()->PositionForPoint(result.LocalPoint());
+  PositionWithAffinity pos_with_affinity = result.GetPosition();
   if (pos_with_affinity.IsNull())
     return false;
   // TODO(xiaochengh): Don't use |ParentAnchoredEquivalent()|.
@@ -1205,8 +1201,9 @@ static bool HitTestResultIsMisspelled(const HitTestResult& result) {
       pos_with_affinity.GetPosition().ParentAnchoredEquivalent();
   if (!SpellChecker::IsSpellCheckingEnabledAt(marker_position))
     return false;
-  return SpellCheckMarkerAtPosition(inner_node->GetDocument().Markers(),
-                                    ToPositionInFlatTree(marker_position));
+  return SpellCheckMarkerAtPosition(
+      result.InnerPossiblyPseudoNode()->GetDocument().Markers(),
+      ToPositionInFlatTree(marker_position));
 }
 
 template <typename MouseEventObject>