Handle overflow more gracefully in chrome://settings/autofill

BUG=469582

Review URL: https://codereview.chromium.org/1036663002

Cr-Commit-Position: refs/heads/master@{#322424}

chrome/browser/resources/options/autofill_options.css

@@ -12,6 +12,9 @@
 
 .autofill-list-item {
   -webkit-padding-start: 8px;
+  max-width: 50%;
+  overflow: hidden;
+  text-overflow: ellipsis;
 }
 
 .autofill-list-item + .deemphasized {