[LayoutNG] Remove NGLineBreaker::overflow_item_index_

r701601 (crrev.com/c/1826063) removed the last use of the
field, but it did not remove the code to set it up.

This patch removes the never-used field.

Change-Id: I291bafccbb0c827213e3b4c890d7589ec5dd3fa7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1838806Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Auto-Submit: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#702808}

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

@@ -299,7 +299,6 @@ void NGLineBreaker::PrepareNextLine(NGLineInfo* line_info) {
   // regardless of 'text-indent'.
   position_ = line_info->TextIndent();
 
-  overflow_item_index_ = 0;
   ResetRewindLoopDetector();
 }
 
@@ -1543,8 +1542,6 @@ bool NGLineBreaker::ShouldHangTraillingSpaces(const NGInlineItem& item) {
 // At this point, item_results does not fit into the current line, and there
 // are no break opportunities in item_results.back().
 void NGLineBreaker::HandleOverflow(NGLineInfo* line_info) {
-  overflow_item_index_ = std::max(overflow_item_index_, item_index_);
-
   // Compute the width needing to rewind. When |width_to_rewind| goes negative,
   // items can fit within the line.
   LayoutUnit available_width = AvailableWidthToFit();
@@ -1645,7 +1642,6 @@ void NGLineBreaker::HandleOverflow(NGLineInfo* line_info) {
     if (!item_results->IsEmpty())
       Rewind(0, line_info);
     state_ = LineBreakState::kContinue;
-    overflow_item_index_ = 0;
     ResetRewindLoopDetector();
     return;
   }

third_party/blink/renderer/core/layout/ng/inline/ng_line_breaker.h

@@ -281,9 +281,6 @@ class CORE_EXPORT NGLineBreaker {
   };
   base::Optional<TrailingCollapsibleSpace> trailing_collapsible_space_;
 
-  // Keep track of item index where overflow occurrred.
-  unsigned overflow_item_index_;
-
   // Keep track of handled float items. See HandleFloat().
   const NGPositionedFloatVector& leading_floats_;
   unsigned leading_floats_index_ = 0u;