Revert "Move toString() to collection classes."

sdk/lib/_collection_dev/iterable.dart

Index: sdk/lib/_collection_dev/iterable.dart
diff --git a/sdk/lib/_collection_dev/iterable.dart b/sdk/lib/_collection_dev/iterable.dart
index 7658baa01369948abf2b78328037eb450d08d7c1..438f574cfb53697e8404afc858348af1b63bb60d 100644
--- a/sdk/lib/_collection_dev/iterable.dart
+++ b/sdk/lib/_collection_dev/iterable.dart
@@ -710,9 +710,6 @@ 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;
@@ -906,27 +903,6 @@ 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);
   }