Reinstall previous behavior for Set and Queue toString.

sdk/lib/internal/iterable.dart

Index: sdk/lib/internal/iterable.dart
diff --git a/sdk/lib/internal/iterable.dart b/sdk/lib/internal/iterable.dart
index 6149cb9f265fe1546fde7a8dadac023a00608526..4cf841801a840490b88d5501340bac09ba45282f 100644
--- a/sdk/lib/internal/iterable.dart
+++ b/sdk/lib/internal/iterable.dart
@@ -741,9 +741,6 @@ abstract class BidirectionalIterator<T> implements Iterator<T> {
  * The uses of this class will be replaced by mixins.
  */
 class IterableMixinWorkaround {
-  // A list to identify cyclic collections during toString() calls.
-  static List _toStringList = new List();
-
   static bool contains(Iterable iterable, var element) {
     for (final e in iterable) {
       if (e == element) return true;
@@ -937,27 +934,6 @@ class IterableMixinWorkaround {
     return buffer.toString();
   }
 
-  static String toStringIterable(Iterable iterable, String leftDelimiter,
-                                 String rightDelimiter) {
-    for (int i = 0; i < _toStringList.length; i++) {
-      if (identical(_toStringList[i], iterable)) {
-        return '$leftDelimiter...$rightDelimiter';
-      }
-    }
-
-    StringBuffer result = new StringBuffer();
-    try {
-      _toStringList.add(iterable);
-      result.write(leftDelimiter);
-      result.writeAll(iterable, ', ');
-      result.write(rightDelimiter);
-    } finally {
-      assert(identical(_toStringList.last, iterable));
-      _toStringList.removeLast();
-    }
-    return result.toString();
-  }
-
   static Iterable where(Iterable iterable, bool f(var element)) {
     return new WhereIterable(iterable, f);
   }