[NGFragmentItem] Fix hit test on left edge of RTL inline element

This patch changes |NGInlineCursor::PositionForPointInInlineBox()| to call
|NGInlineCursor::PositionForPoint()| for |closest_child_after| like it does
fro |closest_child_before| to make hit test on left edge of RTL inline element
to pass the test[1].

This patch also changes |NGFragmentItem::PositionForPointInText()| to avoid
calculating position for items of |IsGeneratedText()|, e.g. ::before/::after.

This is follow-up of the CL[2] which introduces calling |PositionForPoint()|
for |closest_child_before|.

[1] editing/selection/caret-at-bidi-boundary.html
[2] http://crrev.com/c/2104812 [NGFragmentItem] Fix hit test on
position:relative inline element

Bug: 707656
Change-Id: I8aca51af66a7d1885b7b7c2627cd7f4131b37c47
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2282721
Commit-Queue: Kent Tamura <tkent@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#786076}

third_party/blink/renderer/core/layout/ng/inline/ng_fragment_item.cc

@@ -561,6 +561,8 @@ PositionWithAffinity NGFragmentItem::PositionForPointInText(
     const NGInlineCursor& cursor) const {
   DCHECK_EQ(Type(), kText);
   DCHECK_EQ(cursor.CurrentItem(), this);
+  if (IsGeneratedText())
+    return PositionWithAffinity();
   const unsigned text_offset = TextOffsetForPoint(point, cursor.Items());
   const NGCaretPosition unadjusted_position{
       cursor, NGCaretPositionType::kAtTextOffset, text_offset};

third_party/blink/renderer/core/layout/ng/inline/ng_inline_cursor.cc

@@ -869,8 +869,15 @@ PositionWithAffinity NGInlineCursor::PositionForPointInInlineBox(
     if (const PositionWithAffinity child_position =
             descendants.PositionForPointInChild(point))
       return child_position;
-    // TODO(yosin): we should do like "closest_child_before" once we have a
-    // case.
+    if (closest_child_after->BoxFragment()) {
+      // Hit test at left of "12"[1] and after "cd"[2] reache here.
+      // "<span dir="rtl">12<b>&#x05E7;&#x05D0;43</b></span>ab"
+      // [1] "editing/selection/caret-at-bidi-boundary.html"
+      // [2] HitTestingTest.PseudoElementAfter
+      if (const PositionWithAffinity child_position =
+              descendants.PositionForPointInInlineBox(point))
+        return child_position;
+    }
   }
 
   if (closest_child_before) {
@@ -881,7 +888,9 @@ PositionWithAffinity NGInlineCursor::PositionForPointInInlineBox(
     if (closest_child_before->BoxFragment()) {
       // LayoutViewHitTest.HitTestHorizontal "Top-right corner (outside) of div"
       // reach here.
-      return descendants.PositionForPointInInlineBox(point);
+      if (const PositionWithAffinity child_position =
+              descendants.PositionForPointInInlineBox(point))
+        return child_position;
     }
   }