Create associated packages for the dart:collection and dart:async libs.

pkg/collection/test/algorithms_test.dart

Index: pkg/collection/test/algorithms_test.dart
diff --git a/pkg/collection_helpers/test/algorithms_test.dart b/pkg/collection/test/algorithms_test.dart
similarity index 99%
rename from pkg/collection_helpers/test/algorithms_test.dart
rename to pkg/collection/test/algorithms_test.dart
index ff82fff73f43feef4fb1e9531fb1cff190c1baf8..933e268ea6728f58f1938ce01b7017e0fe2282f9 100644
--- a/pkg/collection_helpers/test/algorithms_test.dart
+++ b/pkg/collection/test/algorithms_test.dart
@@ -4,7 +4,7 @@
 
 /// Tests algorithm utilities.
 
-import "package:collection_helpers/all.dart";
+import "package:collection/collection.dart";
 import "package:unittest/unittest.dart";
 import 'dart:math';
 
@@ -268,4 +268,4 @@ class OC implements Comparable<OC> {
   OC(this.id, this.order);
   int compareTo(OC other) => id - other.id;
   String toString() => "OC[$id,$order]";
-}
+}