Deprecate Set.isSubsetOf, make Set.containsAll accept 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 829e801459b558569f7049041addccbffd79c32e..8a4d566130ce6b821fdda7af8dc53518ac83a215 100644
--- a/sdk/lib/collection/linked_hash_set.dart
+++ b/sdk/lib/collection/linked_hash_set.dart
@@ -128,12 +128,19 @@ class LinkedHashSet<E> extends Collection<E> implements Set<E> {
   }
 
   // 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) {