Reinstall previous behavior for Set and Queue toString.

sdk/lib/collection/list.dart

Index: sdk/lib/collection/list.dart
diff --git a/sdk/lib/collection/list.dart b/sdk/lib/collection/list.dart
index 7669a70a5bba94806fb18257b019807330157ae4..b6e1a11b66e2882ebfc6701a9ecaf54787d7a460 100644
--- a/sdk/lib/collection/list.dart
+++ b/sdk/lib/collection/list.dart
@@ -4,9 +4,6 @@
 
 part of dart.collection;
 
-/** A reusable set used to identify cyclic lists during toString() calls. */
-Set _toStringVisiting = new HashSet.identity();
-
 /**
  * Abstract implementation of a list.
  *
@@ -22,7 +19,16 @@ Set _toStringVisiting = new HashSet.identity();
  * to the growable list, or, preferably, use `DelegatingList` from
  * "package:collection/wrappers.dart" instead.
  */
-abstract class ListBase<E> = Object with ListMixin<E>;
+abstract class ListBase<E> extends Object with ListMixin<E> {
+  /**
+   * Convert a `List` to a string as `[each, element, as, string]`.
+   *
+   * Handles circular references where converting one of the elements
+   * to a string ends up converting [list] to a string again.
+   */
+  static String listToString(List list) =>
+      IterableBase.iterableToFullString(list, '[', ']');
+}
 
 /**
  * Base implementation of a [List] class.
@@ -501,21 +507,5 @@ abstract class ListMixin<E> implements List<E> {
 
   Iterable<E> get reversed => new ReversedListIterable(this);
 
-  String toString() {
-    if (_toStringVisiting.contains(this)) {
-      return '[...]';
-    }
-
-    var result = new StringBuffer();
-    try {
-      _toStringVisiting.add(this);
-      result.write('[');
-      result.writeAll(this, ', ');
-      result.write(']');
-     } finally {
-       _toStringVisiting.remove(this);
-     }
-
-    return result.toString();
-  }
+  String toString() => IterableBase.iterableToFullString(this, '[', ']');
 }