Make Iterable.toList more efficient if the length is known.

sdk/lib/collection/queue.dart

Index: sdk/lib/collection/queue.dart
diff --git a/sdk/lib/collection/queue.dart b/sdk/lib/collection/queue.dart
index 816f62e78c4b59bb8187c658952229db169893f3..386cf50a03b6f36dcbceb28107c4063ea7bdf253 100644
--- a/sdk/lib/collection/queue.dart
+++ b/sdk/lib/collection/queue.dart
@@ -444,7 +444,7 @@ class _DoubleLinkedQueueIterator<E> implements Iterator<E> {
  *
  * The structure is efficient for any queue or stack usage.
  */
-class ListQueue<E> extends Iterable<E> implements Queue<E> {
+class ListQueue<E> extends ListIterable<E> implements Queue<E> {
   static const int _INITIAL_CAPACITY = 8;
   List<E> _table;
   int _head;
@@ -478,7 +478,7 @@ class ListQueue<E> extends Iterable<E> implements Queue<E> {
   factory ListQueue.from(Iterable elements) {
     if (elements is List) {
       int length = elements.length;
-      ListQueue<E> queue = new ListQueue(length + 1);
+      ListQueue<E> queue = new ListQueue<E>(length + 1);
       assert(queue._table.length > length);
       for (int i = 0; i < length; i++) {
         queue._table[i] = elements[i] as Object/*=E*/;