a few more strong-mode fixes

R=nweiz@google.com

Review URL: https://codereview.chromium.org//1827353003 .
diff --git a/pubspec.yaml b/pubspec.yaml
index 3697fe6..e5b13cc 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,8 @@
 name: matcher
-version: 0.12.0+2
+
+# This version should really be 0.12.1-dev, but test depends on matcher <0.12.1,
+# so we're using + instead.
+version: 0.12.0+dev
 author: Dart Team <misc@dartlang.org>
 description: Support for specifying test expectations
 homepage: https://github.com/dart-lang/matcher
diff --git a/test/pretty_print_test.dart b/test/pretty_print_test.dart
index c71a94f..551db45 100644
--- a/test/pretty_print_test.dart
+++ b/test/pretty_print_test.dart
@@ -120,7 +120,7 @@
     });
 
     test("that's recursive", () {
-      var list = [1, 2, 3];
+      var list = <dynamic>[1, 2, 3];
       list.add(list);
       expect(prettyPrint(list), equals("[1, 2, 3, (recursive)]"));
     });
diff --git a/test/test_utils.dart b/test/test_utils.dart
index ffcb623..a0dad48 100644
--- a/test/test_utils.dart
+++ b/test/test_utils.dart
@@ -2,8 +2,6 @@
 // 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 'dart:collection';
-
 import 'package:test/test.dart';
 
 void shouldFail(value, Matcher matcher, expected) {
@@ -43,25 +41,12 @@
   featureValueOf(actual) => actual.price;
 }
 
-class SimpleIterable extends IterableBase<int> {
+class SimpleIterable extends Iterable<int> {
   final int count;
 
   SimpleIterable(this.count);
 
-  bool contains(int val) => count < val ? false : true;
-
-  bool any(bool f(element)) {
-    for (var i = 0; i <= count; i++) {
-      if (f(i)) return true;
-    }
-    return false;
-  }
-
-  String toString() => "<[$count]>";
-
-  Iterator get iterator {
-    return new _SimpleIterator(count);
-  }
+  Iterator<int> get iterator => new _SimpleIterator(count);
 }
 
 class _SimpleIterator implements Iterator<int> {