[paint] Remove additional ScopedPaintTimingDetectorBlockPaintHook.

Followup from:
https://chromium-review.googlesource.com/c/chromium/src/+/2044522/3/third_party/blink/renderer/core/paint/ng/ng_box_fragment_painter.cc#325

I was pointed out that now we have the
ScopedPaintTimingDetectorBlockPaintHook within PaintInternal, the one
within PaintLineBoxChildren was redundant.

Change-Id: I285ce15eba904c1c21e24e94ce87cf86184edec8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2076080Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Nicolás Peña Moreno <npm@chromium.org>
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745116}

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

@@ -1200,17 +1200,8 @@ void NGBoxFragmentPainter::PaintLineBoxChildren(
   if (!*children)
     return;
 
-  ScopedPaintTimingDetectorBlockPaintHook
-      scoped_paint_timing_detector_block_paint_hook;
-  const auto& layout_block = To<LayoutBlock>(*layout_object);
-  if (paint_info.phase == PaintPhase::kForeground) {
-    scoped_paint_timing_detector_block_paint_hook.EmplaceIfNeeded(
-        layout_block,
-        paint_info.context.GetPaintController().CurrentPaintChunkProperties());
-  }
-
   if (paint_info.phase == PaintPhase::kForcedColorsModeBackplate &&
-      layout_block.GetDocument().InForcedColorsMode()) {
+      layout_object->GetDocument().InForcedColorsMode()) {
     PaintBackplate(children, paint_info, paint_offset);
     return;
   }