Call super from finalizeCollectionViewUpdates.

Add missing call to super from finalizeCollectionViewUpdates inside the
Tab Switcher Layout.

Bug: 1127604
Change-Id: I109b5bd16a64351231857f5447c940e54452d68b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2440609
Commit-Queue: Roberto Moura <mouraroberto@google.com>
Auto-Submit: Roberto Moura <mouraroberto@google.com>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813177}

ios/chrome/browser/ui/tab_grid/grid/tab_switcher_layout.mm

@@ -117,6 +117,7 @@
 - (void)finalizeCollectionViewUpdates {
   self.indexPathsOfDeletingItems = @[];
   self.indexPathsOfInsertingItems = @[];
+  [super finalizeCollectionViewUpdates];
 }
 
 @end