Free the C memory for ArchiveInputStream when the stream is garbage collected.

utils/archive/utils.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("utils");
 
 #import("dart-ext:dart_archive");
 #import("dart:isolate");
 #import("archive.dart", prefix: "archive");
 
@@ skipping 40 matching lines @@
 }
 
 /** Converts [input] to a [Uint8List] that C can process easily. */
 Uint8List bytesForC(List<int> input) {
   var list = new Uint8List(input.length);
   list.setRange(0, input.length, input);
   return list;
 }
 
 /**
+ * Attaches [callback] as a finalizer for [object]. After [object] has been
+ * garbage collected, [callback] will be called and passed [peer] as an
+ * argument.
+ *
+ * Neither [callback] nor [peer] should contain any references to [object];
+ * otherwise, [object] will never be collected and [callback] will never be
+ * called.
+ */
+void attachFinalizer(object, void callback(peer), [peer])
+    native "Archive_AttachFinalizer";
+
+/**
+ * A reference to a single value.
+ *
+ * This is primarily meant to be used when a finalizer needs to refer to a field
+ * on the object being finalized that may be set to null during the lifetime of
+ * the object. Since the object itself has been garbage collected once the
+ * finalizer runs, it needs a second-order reference to check if the field is
+ * null.
+ */
+class Reference<E> {
+  E value;
+  Reference(this.value);
+}
+
+/**
  * Returns a [Future] that completes immediately upon hitting the event loop.
  */
 Future async() {
   var completer = new Completer();
   new Timer(0, (_) => completer.complete(null));
   return completer.future;
 }
 
 /** An error raised by the archive library. */
 class ArchiveException implements archive.ArchiveException {
   /** A description of the error that occurred. */   
   final String message;
 
   /** The error code for the error, or null. */
   final int errno;
 
   ArchiveException(this.message, [this.errno]);
 
   String toString() {
     if (errno == null) return "Archive error: $message";
     return "Archive error $errno: $message";
   }
 }