Deprecate Set.isSubsetOf, make Set.containsAll accept iterable.

sdk/lib/collection/hash_set.dart

 // Copyright (c) 2013, 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.
 
 part of dart.collection;
 
 class HashSet<E> extends Collection<E> implements Set<E> {
   static const int _INITIAL_CAPACITY = 8;
   final _HashTable<E> _table;
 
@@ skipping 68 matching lines @@
 
   void retainWhere(bool test(E element)) {
     _filterWhere(test, false);
   }
 
   void clear() {
     _table._clear();
   }
 
   // Set.
-  bool isSubsetOf(Set<E> other) {
-    return IterableMixinWorkaround.isSubsetOfSet(this, other);
+  bool isSubsetOf(Collection<E> other) {
+    // Deprecated, and using old signature.
+    Set otherSet;
+    if (other is Set) {
+      otherSet = other;
+    } else {
+      otherSet = other.toSet();
+    }
+    return IterableMixinWorkaround.setContainsAll(otherSet, this);
   }
 
-  bool containsAll(Set<E> other) {
-    return IterableMixinWorkaround.isSubsetOfSet(other, this);
+  bool containsAll(Iterable<E> other) {
+    return IterableMixinWorkaround.setContainsAll(this, other);
   }
 
   Set<E> intersection(Set<E> other) {
     return IterableMixinWorkaround.setIntersection(
         this, other, new HashSet<E>());
   }
 
   Set<E> union(Set<E> other) {
     return IterableMixinWorkaround.setUnion(this, other, new HashSet<E>());
   }
 
   Set<E> difference(Set<E> other) {
     return IterableMixinWorkaround.setDifference(this, other, new HashSet<E>());
   }
 
   String toString() => Collections.collectionToString(this);
 }