Format all dart: library files

sdk/lib/collection/linked_hash_set.dart

Index: sdk/lib/collection/linked_hash_set.dart
diff --git a/sdk/lib/collection/linked_hash_set.dart b/sdk/lib/collection/linked_hash_set.dart
index d07c7e929d3ea0d2f116d54cd72d5ac14cbe29ec..6eda72169a5f2b956e80ff89cd2bd95d9526f794 100644
--- a/sdk/lib/collection/linked_hash_set.dart
+++ b/sdk/lib/collection/linked_hash_set.dart
@@ -74,9 +74,10 @@ abstract class LinkedHashSet<E> implements HashSet<E> {
    * and the `isValidKey` defaults to accepting all keys.
    * Such a map can be created directly using [LinkedHashSet.identity].
    */
-  external factory LinkedHashSet({bool equals(E e1, E e2),
-                                  int hashCode(E e),
-                                  bool isValidKey(potentialKey)});
+  external factory LinkedHashSet(
+      {bool equals(E e1, E e2),
+      int hashCode(E e),
+      bool isValidKey(potentialKey)});
 
   /**
    * Creates an insertion-ordered identity-based set.