Remove Collection, Collections and clean up List/Set/Queue implementations of retain/remove.

tests/corelib/is_operator_basic_types_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.
 // Dart test program for the "is" type test operator.
 
 import "package:expect/expect.dart";
 
 check(args) {
   var list = args[0];
   var string = args[1];
   var nullObject = args[2];
 
   Expect.isTrue(list is Object);
   Expect.isTrue(list is List);
-  Expect.isTrue(list is Collection);
   Expect.isTrue(list is Iterable);
   Expect.isFalse(list is Comparable);
   Expect.isFalse(list is Pattern);
   Expect.isFalse(list is String);
 
   Expect.isFalse(list is !List);
-  Expect.isFalse(list is !Collection);
   Expect.isFalse(list is !Iterable);
   Expect.isTrue(list is !Comparable);
   Expect.isTrue(list is !Pattern);
   Expect.isTrue(list is !String);
 
   Expect.isTrue(string is Object);
   Expect.isFalse(string is List);
-  Expect.isFalse(string is Collection);
   Expect.isFalse(string is Iterable);
   Expect.isTrue(string is Comparable);
   Expect.isTrue(string is Pattern);
   Expect.isTrue(string is String);
 
   Expect.isTrue(string is !List);
-  Expect.isTrue(string is !Collection);
   Expect.isTrue(string is !Iterable);
   Expect.isFalse(string is !Comparable);
   Expect.isFalse(string is !Pattern);
   Expect.isFalse(string is !String);
 
   Expect.isTrue(nullObject is Object);
   Expect.isFalse(nullObject is List);
-  Expect.isFalse(nullObject is Collection);
   Expect.isFalse(nullObject is Iterable);
   Expect.isFalse(nullObject is Comparable);
   Expect.isFalse(nullObject is Pattern);
   Expect.isFalse(nullObject is String);
 
   Expect.isTrue(nullObject is !List);
-  Expect.isTrue(nullObject is !Collection);
   Expect.isTrue(nullObject is !Iterable);
   Expect.isTrue(nullObject is !Comparable);
   Expect.isTrue(nullObject is !Pattern);
   Expect.isTrue(nullObject is !String);
 }
 
 main() {
   // Try to make it hard for an optimizing compiler to inline the
   // tests.
   check([[], 'string', null]);
 
   // Try to make it even harder.
   var string = new String.fromCharCodes([new DateTime.now().year % 100 + 1]);
   check([string.codeUnits, string, null]);
 }