Add Iterable.fold (and Stream.fold) which replace `reduce`.

tests/corelib/list_map_test.dart

 // Copyright (c) 2012, 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.
 
 
 main() {
   testOperations();
 }
 
 class ThrowMarker {
@@ skipping 97 matching lines @@
     testOp((i) => i.singleWhere((n) => n < 10), "singelWhere<10");
     testOp((i) => i.singleWhere((n) => true), "singleWhere<true");
     testOp((i) => i.contains(5), "contains(5)");
     testOp((i) => i.contains(10), "contains(10)");
     testOp((i) => i.any((n) => n < 5), "any<5");
     testOp((i) => i.any((n) => n < 10), "any<10");
     testOp((i) => i.every((n) => n < 5), "every<5");
     testOp((i) => i.every((n) => n < 10), "every<10");
     testOp((i) => i.max(), "max");
     testOp((i) => i.min(), "min");
     testOp((i) => i.reduce(0, (a, b) => a + b), "reduce-sum");

[Lasse Reichstein Nielsen, 2013/04/04 08:35:18]

Remove the reduce line. It's deprecated.

[floitsch, 2013/04/05 16:10:03]

I prefer keeping it. When I change the reduce to the new behavior I will get an
error during tests and make sure to add a new test-case.

+    testOp((i) => i.fold(0, (a, b) => a + b), "fold-sum");
     testOp((i) => i.join("-"), "join-");
     testOp((i) => i.join(""), "join");
     testOp((i) => i.join(), "join-null");
     testOp((i) => i.map((n) => n * 2), "map*2");
     testOp((i) => i.where((n) => n < 5), "where<5");
     testOp((i) => i.where((n) => n < 10), "where<10");
     testOp((i) => i.expand((n) => []), "expand[]");
     testOp((i) => i.expand((n) => [n]), "expand[n]");
     testOp((i) => i.expand((n) => [n, n]), "expand[n, n]");
     testOp((i) => i.take(0), "take(0)");
@@ skipping 26 matching lines @@
   testList([0, 1, 2, 3]);
   testList([3, 4, 5, 6]);
   testList([10, 11, 12, 13]);
   testList(l);
   testList(r);
   testList(base);
 
   // Reverse const list.
   Expect.listEquals(r, l.map(rev).toList());
 }