Migrated test block 26 to Dart 2.0.

tests/corelib_2/splay_tree_from_iterable_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.
 
 import "package:expect/expect.dart";
 import 'dart:collection';
 
 main() {
   defaultFunctionValuesTest();
   defaultKeyFunctionTest();
@@ skipping 108 matching lines @@
   Expect.isFalse(map is SplayTreeMap<dynamic, int>);
 }
 
 typedef String intToString(int v);
 typedef bool intToBool(int v);
 
 // Test in checked mode with explicitly given types.
 void typedTest() {
   bool isCheckedMode = false;
   assert((isCheckedMode = true));
   if (!isCheckedMode) return;

[Bob Nystrom, 2017/07/24 22:27:43]

Dart 2.0 doesn't have checked mode anymore (or, perhaps more accurately, it
doesn't have *unchecked* mode), so you'll want to remove this check and always
execute these tests.

In many cases, the checked mode tests will end up getting deleted because the
code under test also has a static error so there is no runtime behavior in
strong mode. SplayTreeMap.fromIterable() is a little different because it isn't
as fully-typed as we'd like — it takes an Iterable<dynamic> instead of a more
precisely typed iterable. That means the type checks do happen at runtime, so I
think these tests are valid.

 
   // Assign functions to typed function variables.
   intToString key = (int v) => "$v";
   intToBool value = (int v) => v.isOdd;
   Function id = (int i) => i;
 
   Expect.throws(() {
     new SplayTreeMap<String, bool>.fromIterable(<int>[1, 2, 3], key: key
         // No "value" map, defaults to identity, which returns int, not bool.
         );
@@ skipping 23 matching lines @@
       key: key, value: value);
   Iterable<String> keys = map.keys;
   Iterable<bool> values = map.values;
   List<String> keyList = keys.toList();
   List<bool> valueList = values.toList();
   Expect.equals(3, keyList.length);
   Expect.equals(3, valueList.length);
   Expect.equals(keys.first, map.firstKey());
   Expect.equals(keys.last, map.lastKey());
 }