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

sdk/lib/_internal/compiler/implementation/elements/elements.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.
 
 library elements;
 
 import 'dart:uri';
 
 import 'modelx.dart';
 import '../tree/tree.dart';
@@ skipping 444 matching lines @@
     return (element == coreLibrary.find(const SourceString('Comparable')));
   }
 
   static bool isStringOnlySupertype(Element element, Compiler compiler) {
     LibraryElement coreLibrary = compiler.coreLibrary;
     return element == coreLibrary.find(const SourceString('Pattern'));
   }
 
   static bool isListSupertype(Element element, Compiler compiler) {
     LibraryElement coreLibrary = compiler.coreLibrary;
-    return (element == coreLibrary.find(const SourceString('Collection')))
-        || (element == coreLibrary.find(const SourceString('Iterable')));
+    return element == coreLibrary.find(const SourceString('Iterable'));
   }
 
   /// A `compareTo` function that places [Element]s in a consistent order based
   /// on the source code order.
   static int compareByPosition(Element a, Element b) {
     CompilationUnitElement unitA = a.getCompilationUnit();
     CompilationUnitElement unitB = b.getCompilationUnit();
     if (!identical(unitA, unitB)) {
       int r = unitA.script.uri.path.compareTo(unitB.script.uri.path);
       if (r != 0) return r;
@@ skipping 384 matching lines @@
   int get resolutionState;
   Token get beginToken;
   Token get endToken;
 
   // TODO(kasperl): Try to get rid of these.
   void set annotatedElement(Element value);
   void set resolutionState(int value);
 
   MetadataAnnotation ensureResolved(Compiler compiler);
 }