Add missing output file to devtools_grd_files

Bug: none
Change-Id: Id9ee801004b890257d7f0057244fb4015b0e528c
No-Presubmit: True
No-Tree-Checks: True
No-Try: True
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6725116
Commit-Queue: Alex Rudenko <[email protected]>
Reviewed-by: Alex Rudenko <[email protected]>
Auto-Submit: Jack Franklin <[email protected]>

Author: jackfranklin

config/gni/devtools_grd_files.gni

@@ -1894,6 +1894,7 @@ grd_files_unbundled_sources = [
   "front_end/panels/timeline/TimelinePaintProfilerView.js",
   "front_end/panels/timeline/TimelinePanel.js",
   "front_end/panels/timeline/TimelineSelection.js",
+  "front_end/models/elements/ElementUpdateRecord.js",
   "front_end/panels/timeline/TimelineSelectorStatsView.js",
   "front_end/panels/timeline/TimelineTreeView.js",
   "front_end/panels/timeline/TimelineUIUtils.js",