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

lib/collection/collections.dart

Index: lib/collection/collections.dart
diff --git a/lib/coreimpl/collections.dart b/lib/collection/collections.dart
similarity index 97%
rename from lib/coreimpl/collections.dart
rename to lib/collection/collections.dart
index 873e9cdf121d104766d21507006308b07f769d11..2bee21c1b59ae06ec681f609edc82b9aeb1d2fee 100644
--- a/lib/coreimpl/collections.dart
+++ b/lib/collection/collections.dart
@@ -100,7 +100,9 @@ class Collections {
    * 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 ? '[' : '{');