Drop copy of combineAllMatcher

This can be pulled in from the latest package:test

pkgs/stream_transform/pubspec.yaml

diff --git a/pkgs/stream_transform/pubspec.yaml b/pkgs/stream_transform/pubspec.yaml
index 3d096dc..15c2bbe 100644
--- a/pkgs/stream_transform/pubspec.yaml
+++ b/pkgs/stream_transform/pubspec.yaml
@@ -8,4 +8,4 @@
   sdk: ">=1.22.0 <2.0.0"
 
 dev_dependencies:
-  test: ^0.12.0
+  test: ^0.12.20+13

pkgs/stream_transform/test/merge_test.dart

diff --git a/pkgs/stream_transform/test/merge_test.dart b/pkgs/stream_transform/test/merge_test.dart
index 2199ecb..c604f91 100644
--- a/pkgs/stream_transform/test/merge_test.dart
+++ b/pkgs/stream_transform/test/merge_test.dart
@@ -4,8 +4,6 @@
 
 import 'package:stream_transform/stream_transform.dart';
 
-import 'util/matchers.dart';
-
 void main() {
   group('merge', () {
     test('includes all values', () async {

pkgs/stream_transform/test/util/matchers.dart

diff --git a/pkgs/stream_transform/test/util/matchers.dart b/pkgs/stream_transform/test/util/matchers.dart
deleted file mode 100644
index 4028b73..0000000
--- a/pkgs/stream_transform/test/util/matchers.dart
+++ /dev/null
@@ -1,42 +0,0 @@
-import 'package:test/test.dart';
-
-/// Matches [Iterable]s which contain an element matching every value in
-/// [expected] in the same order, but may contain additional values interleaved
-/// throughout.
-Matcher containsAllInOrder(Iterable expected) =>
-    new _ContainsAllInOrder(expected);
-
-class _ContainsAllInOrder implements Matcher {
-  final Iterable _expected;
-
-  _ContainsAllInOrder(this._expected);
-
-  String _test(item, Map matchState) {
-    if (item is! Iterable) return 'not iterable';
-    var matchers = _expected.map(wrapMatcher).toList();
-    var matcherIndex = 0;
-    for (var value in item) {
-      if (matchers[matcherIndex].matches(value, matchState)) matcherIndex++;
-      if (matcherIndex == matchers.length) return null;
-    }
-    return new StringDescription()
-        .add('did not find a value matching ')
-        .addDescriptionOf(matchers[matcherIndex])
-        .add(' following expected prior values')
-        .toString();
-  }
-
-  @override
-  bool matches(item, Map matchState) => _test(item, matchState) == null;
-
-  @override
-  Description describe(Description description) => description
-      .add('contains in order(')
-      .addDescriptionOf(_expected)
-      .add(')');
-
-  @override
-  Description describeMismatch(item, Description mismatchDescription,
-          Map matchState, bool verbose) =>
-      mismatchDescription.add(_test(item, matchState));
-}