Move Arrays, Collections and Maps into a new library, dart:collections.

lib/collection/collections.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.
 
 /**
  * The [Collections] class implements static methods useful when
  * writing a class that implements [Collection] and the [iterator]
  * method.
  */
 class Collections {
@@ skipping 82 matching lines @@
   /**
    * Appends a string representing the specified collection to the specified
    * string buffer. The string is formatted as per [collectionToString].
    * The [:visiting:] list contains references to all of the enclosing
    * collections and maps (which are currently in the process of being
    * emitted into [:result:]). The [:visiting:] parameter allows this method to
    * generate a [:'[...]':] or [:'{...}':] where required. In other words,
    * it allows this method and [_emitMap] to identify recursive collections
    * and maps.
    */
-  static void _emitCollection(Collection c, StringBuffer result, List visiting) {
+  static void _emitCollection(Collection c,
+                              StringBuffer result,
+                              List visiting) {
     visiting.add(c);
     bool isList = c is List;
     result.add(isList ? '[' : '{');
 
     bool first = true;
     for (var e in c) {
       if (!first) {
         result.add(', ');
       }
       first = false;
@@ skipping 39 matching lines @@
    * Returns true if the specified collection contains the specified object
    * reference.
    */
   static _containsRef(Collection c, Object ref) {
     for (var e in c) {
       if (e === ref) return true;
     }
     return false;
   }
 }