[WebUI][NTP] Makes the hyphen in realbox matches appear "dimmed"

Bug: 1098131
Change-Id: Id6f0c9e3f1217be1e6a219e62d9fd25c5280baad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2264800
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Commit-Queue: Tibor Goldschwendt <tiborg@chromium.org>
Auto-Submit: Moe Ahmadi <mahmadi@chromium.org>
Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#781979}

chrome/browser/resources/new_tab_page/realbox_match.html

@@ -78,7 +78,7 @@
 <ntp-realbox-icon id="icon" match="[[match]]"></ntp-realbox-icon>
 <div id="container">
   <span id="contents" inner-h-t-m-l="[[contentsHtml_]]"></span>
-  <span id="separator">[[separatorText_]]</span>
+  <span id="separator" class="dim">[[separatorText_]]</span>
   <span id="description" inner-h-t-m-l="[[descriptionHtml_]]"></span>
 </div>
 <ntp-realbox-button id="remove" tabindex="0" role="button"