Revert "Make EfficientLength public, as EfficientLengthIterable."

tests/corelib/growable_list_test.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // Sanity check on the growing behavior of a growable list.
 
 import "package:expect/expect.dart";
-import "dart:collection" show EfficientLengthIterable;
+import "dart:collection" show IterableBase;
 
 // Iterable generating numbers in range [0..count).
 // May perform callback at some point underways.
-class TestIterableBase extends Iterable<int> {
+class TestIterableBase extends IterableBase<int> {
   final int length;
   final int count;
   // call [callback] if generating callbackIndex.
   final int callbackIndex;
   final Function callback;
   TestIterableBase(this.length, this.count,
                    this.callbackIndex, this.callback);
   Iterator<int> get iterator => new CallbackIterator(this);
 }
 
 class TestIterable extends TestIterableBase {
   TestIterable(count, [callbackIndex = -1, callback])
       : super(-1, count, callbackIndex, callback);
   int get length => throw "SHOULD NOT BE CALLED";
 }
 
+// Implement Set for private EfficientLength interface.
 class EfficientTestIterable extends TestIterableBase
-                            implements EfficientLengthIterable<int> {
+                            implements Set<int> {
   EfficientTestIterable(length, count, [callbackIndex = -1, callback])
       : super(length, count, callbackIndex, callback);
   // Avoid warnings because we don't actually implement Set.
   noSuchMethod(i) => super.noSuchMethod(i);
 }
 
 class CallbackIterator implements Iterator<int> {
   TestIterableBase _iterable;
   int _current = null;
   int _nextIndex = 0;
   CallbackIterator(this._iterable);
   bool moveNext() {
     if (_nextIndex >= _iterable.count) {
       _current = null;
       return false;
     }
     _current = _nextIndex;
     _nextIndex++;
     if (_current == _iterable.callbackIndex) {
       _iterable.callback();
     }
     return true;
   }
   int get current => _current;
 }
 
 
 void main() {
-  // Without EfficientLengthIterable interface
+  // Without EfficientLength interface
   {
     // Change length of list after 20 additions.
     var l = [];
     var ci = new TestIterable(257, 200, () {
       l.add("X");
     });
     Expect.throws(() {
       l.addAll(ci);
     }, (e) => e is ConcurrentModificationError);
   }
 
   {
     // Change length of list after 20 additions.
     var l = [];
     var ci = new TestIterable(257, 200, () {
       l.length = 0;
     });
     Expect.throws(() {
       l.addAll(ci);
     }, (e) => e is ConcurrentModificationError);
   }
 
-  // With EfficientLengthIterable interface (uses length).
+  // With EfficientLength interface (uses length).
   {
     // Change length of list after 20 additions.
     var l = [];
     var ci = new EfficientTestIterable(257, 257, 20, () {
       l.add("X");
     });
     Expect.throws(() {
       l.addAll(ci);
     }, (e) => e is ConcurrentModificationError);
   }
@@ skipping 30 matching lines @@
     Expect.throws(() { l.addAll(l); }, (e) => e is ConcurrentModificationError);
   }
 
   {
     // Adding to yourself.
     var l = [1, 2, 3];
     Expect.throws(() { l.addAll(l); }, (e) => e is ConcurrentModificationError);
   }
 }