[chrome://omnibox]: Fix filter color not applying to gray rows.

The previous CL crrev.com/c/1680983 introduced compact rows with
alternating white & gray background colors. Because of CSS selector
specificity, the gray background prevented the filter background
applying.

Change-Id: I277e4e64ec9709c3da9f24f2e01adb59604c1046
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1692210Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#675726}

chrome/browser/resources/omnibox/output_results_group.css

@@ -83,13 +83,13 @@ table {
   white-space: pre-wrap;
 }
 
-.body tr.thin:nth-child(even) td {
+.body tr.thin:nth-child(even) {
   background-color: #fafafa;
 }
 
-.body tr:hover td,
+.body tr:hover,
 /* must explicitly select .thin tr's to override above .thin styling */
-.body tr.thin:hover td {
+.body tr.thin:hover {
   background-color: var(--row-hover-color);
 }
 
@@ -285,10 +285,10 @@ img:not([src]),
 
 /* filter */
 
-.filtered-highlighted {
+.body tr.filtered-highlighted:not(:hover) {
   background-color: rgb(208, 240, 255);
 }
 
-.filtered-highlighted-nested {
+.body tr.filtered-highlighted:not(:hover) td.filtered-highlighted-nested {
   background-color: rgb(208, 255, 208);
 }