MD Settings: Restore Search engines table headers.

chrome/browser/resources/settings/search_engines_page/search_engine_entry_css.html

 <dom-module id="search-engine-entry">
   <template>
     <style>
       .favicon-image {
         -webkit-margin-end: 8px;
         background-repeat: no-repeat;
         background-size: contain;
         display: inline-block;
         height: 20px;
+        min-width: 20px;
         vertical-align: middle;
-        width: 20px;
       }
 
       .name {
         margin: auto;
       }
 
       .dropdown-content {
         background: white;
         box-shadow: 0 2px 6px grey;
       }
     </style>
   </template>
 </dom-module>