Fix thinking_face emoji autocomplete (#5238)

app/javascript/mastodon/features/emoji/emoji_utils.js

@@ -125,13 +125,16 @@ function getData(emoji) {
 }
 
 function intersect(a, b) {
-  let aSet = new Set(a);
-  let bSet = new Set(b);
-  let intersection = new Set(
-    [...aSet].filter(x => bSet.has(x))
-  );
-
-  return Array.from(intersection);
+  let set;
+  let list;
+  if (a.length < b.length) {
+    set = new Set(a);
+    list = b;
+  } else {
+    set = new Set(b);
+    list = a;
+  }
+  return Array.from(new Set(list.filter(x => set.has(x))));
 }
 
 export { getData, getSanitizedData, intersect };