DevTools: Account for scale in CSS Grid Computed Track Labels

This cl fixes a bug where scale was not applied to the positioning
of the computed track size labels for CSS Grid overlay, causing
them to be misplaced on high dpi monitors.

Before: https://imgur.com/B970mXx

After: https://imgur.com/GLR5s2l

Bug: 1109014
Change-Id: Id762b7ef04041ff8fffe9db958dfc58585858cd8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2316793
Commit-Queue: Alex Rudenko <alexrudenko@chromium.org>
Reviewed-by: Alex Rudenko <alexrudenko@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791724}

third_party/blink/renderer/core/inspector/inspector_highlight.cc

@@ -426,8 +426,8 @@ std::unique_ptr<protocol::ListValue> BuildGridTrackSizes(
                                direction == kForColumns ? 0 : offset);
     FloatPoint abs_arrow_pos =
         layout_grid->LocalToAbsoluteFloatPoint(local_arrow_pos);
-    size_info->setDouble("x", abs_arrow_pos.X());
-    size_info->setDouble("y", abs_arrow_pos.Y());
+    size_info->setDouble("x", abs_arrow_pos.X() * scale);
+    size_info->setDouble("y", abs_arrow_pos.Y() * scale);
     sizes->pushValue(std::move(size_info));
     start += track;
     i++;