typeahead: Restore line height to original value.

e5e5ba6cea reduce the line height
of the typeaheads, which doesn't look for stream typeaheads. We
restore it back to original value.

web/styles/typeahead.css

@@ -25,7 +25,7 @@
             font-weight: normal;
             /* We want to keep this `max-width` less than 320px. */
             max-width: 292px;
-            line-height: var(--base-line-height-unitless);
+            line-height: 1.43; /* 20px / 14px */
             color: var(--color-dropdown-item);
             white-space: nowrap;