[NTP] Fix copy paste error.

Code was referencing undefined variables.

Bug: 853780
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Change-Id: Ie50c336424a45f780b854b35074b788be65a9368
Reviewed-on: https://chromium-review.googlesource.com/1104779Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: Mathieu Perreault <mathp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568106}

chrome/browser/resources/local_ntp/most_visited_single.js

@@ -636,7 +636,7 @@ function renderMaterialDesignTile(data) {
     });
     fi.addEventListener('error', function(ev) {
       mdFavicon.classList.add(CLASSES.FAILED_FAVICON);
-      thumb.removeChild(img);
+      mdFavicon.removeChild(fi);
       // Store the type for a potential later navigation.
       tileType = TileVisualType.ICON_DEFAULT;
       logMostVisitedImpression(