[FragmentItem] All items are initially first and last for node.

NGFragmentItems::FinalizeAfterLayout() will typically update the bits
after layout, but apparently not always.

This should have been part of CL:2169929

This hopefully fixes:
https://ci.chromium.org/p/chromium/builders/ci/WebKit%20Linux%20MSAN/5530
https://ci.chromium.org/p/chromium/builders/ci/Win7%20Tests%20%281%29/102130

TBR=kojii@chromium.org

Bug: 1075993
Change-Id: I53207183f6fa7f9c4ccd7db6b64fa8e5c755c332
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2170098Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#763415}

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

@@ -25,7 +25,8 @@ NGFragmentItem::NGFragmentItem(const NGPhysicalTextFragment& text)
       is_hidden_for_paint_(text.IsHiddenForPaint()),
       text_direction_(static_cast<unsigned>(text.ResolvedDirection())),
       ink_overflow_computed_(false),
-      is_first_for_node_(text.IsFirstForNode()) {
+      is_first_for_node_(true),
+      is_last_for_node_(true) {
 #if DCHECK_IS_ON()
   if (text_.shape_result) {
     DCHECK_EQ(text_.shape_result->StartIndex(), StartOffset());
@@ -53,7 +54,8 @@ NGFragmentItem::NGFragmentItem(NGInlineItemResult&& item_result,
       is_hidden_for_paint_(false),  // TODO(kojii): not supported yet.
       text_direction_(static_cast<unsigned>(item_result.item->Direction())),
       ink_overflow_computed_(false),
-      is_first_for_node_(item_result.IsFirstForNode()) {
+      is_first_for_node_(true),
+      is_last_for_node_(true) {
 #if DCHECK_IS_ON()
   if (text_.shape_result) {
     DCHECK_EQ(text_.shape_result->StartIndex(), StartOffset());
@@ -76,7 +78,8 @@ NGFragmentItem::NGFragmentItem(const NGPhysicalLineBoxFragment& line,
       is_hidden_for_paint_(false),
       text_direction_(static_cast<unsigned>(line.BaseDirection())),
       ink_overflow_computed_(false),
-      is_first_for_node_(true) {
+      is_first_for_node_(true),
+      is_last_for_node_(true) {
   DCHECK(!IsFormattingContextRoot());
 }
 
@@ -90,7 +93,8 @@ NGFragmentItem::NGFragmentItem(const NGPhysicalBoxFragment& box,
       is_hidden_for_paint_(box.IsHiddenForPaint()),
       text_direction_(static_cast<unsigned>(resolved_direction)),
       ink_overflow_computed_(false),
-      is_first_for_node_(box.IsFirstForNode()) {
+      is_first_for_node_(true),
+      is_last_for_node_(true) {
   DCHECK_EQ(IsFormattingContextRoot(), box.IsFormattingContextRoot());
 }
 
@@ -104,7 +108,8 @@ NGFragmentItem::NGFragmentItem(const NGInlineItem& inline_item,
       is_hidden_for_paint_(false),
       text_direction_(static_cast<unsigned>(TextDirection::kLtr)),
       ink_overflow_computed_(false),
-      is_first_for_node_(true) {
+      is_first_for_node_(true),
+      is_last_for_node_(true) {
   DCHECK_EQ(inline_item.Type(), NGInlineItem::kOpenTag);
   DCHECK(layout_object_);
   DCHECK(layout_object_->IsLayoutInline());