Change List/Set/Map/Queue.from constructrs to accept any iterable.

sdk/lib/collection/linked_hash_set.dart

Index: sdk/lib/collection/linked_hash_set.dart
diff --git a/sdk/lib/collection/linked_hash_set.dart b/sdk/lib/collection/linked_hash_set.dart
index c96d94db571720155511ac3a7bbf228603b5da95..af13525c8b5d03a824c4d3e9dc7cfdebef0d2176 100644
--- a/sdk/lib/collection/linked_hash_set.dart
+++ b/sdk/lib/collection/linked_hash_set.dart
@@ -65,8 +65,26 @@ abstract class LinkedHashSet<E> implements HashSet<E> {
    */
   external factory LinkedHashSet.identity();
 
-  factory LinkedHashSet.from(Iterable<E> iterable) {
-    return new LinkedHashSet<E>()..addAll(iterable);
+  /**
+   * Create a linked hash set containing all of [elements].
+   *
+   * Creates a linked hash set as by `new LinkedHashSet<E>()` and adds each
+   * element of`elements` to this set in the order they are iterated.
+   *
+   * All the [elements] should be assignable to [E].
+   * The `elements` iterable itself may have any element type,
+   * so this constructor can be used to down-cast a `Set`, for example as:
+   *
+   *     Set<SuperType> superSet = ...;
+   *     Iterable<SuperType> tmp = superSet.where((e) => e is SubType);
+   *     Set<SubType> subSet = new LinkedHashSet<SubType>.from(tmp);
+   */
+  factory LinkedHashSet.from(Iterable<E> elements) {
+    LinkedHashSet<E> result = new LinkedHashSet<E>();
+    for (final E element in elements) {

[Søren Gjesse, 2015/01/05 15:35:15]

Any particular reason for using final here?

[Lasse Reichstein Nielsen, 2015/01/06 10:14:45]

No. Copied it from somewhere else that had a final.
No reason not to make it final either.

+      result.add(element);
+    }
+    return result;
   }
 
   /**