Reduce usage of ItearbleMixinWorkaround.

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 8a4d566130ce6b821fdda7af8dc53518ac83a215..f33ab54b89b51245f6c444dfeaf10d6698985b5b 100644
--- a/sdk/lib/collection/linked_hash_set.dart
+++ b/sdk/lib/collection/linked_hash_set.dart
@@ -4,7 +4,8 @@
 
 part of dart.collection;
 
-class LinkedHashSet<E> extends Collection<E> implements Set<E> {
+class LinkedHashSet<E> extends Collection<E> with _SetMixin<E>
+                       implements Set<E> {
   static const int _INITIAL_CAPACITY = 8;
   _LinkedHashTable<E> _table;
 
@@ -93,10 +94,6 @@ class LinkedHashSet<E> extends Collection<E> implements Set<E> {
     }
   }
 
-  void retainAll(Iterable objectsToRemove) {
-    IterableMixinWorkaround.retainAll(this, objectsToRemove);
-  }
-
   void _filterWhere(bool test(E element), bool removeMatching) {
     int entrySize = _table._entrySize;
     int length = _table._table.length;
@@ -127,36 +124,8 @@ class LinkedHashSet<E> extends Collection<E> implements Set<E> {
     _table._clear();
   }
 
-  // Set.
-  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(Iterable<E> other) {
-    return IterableMixinWorkaround.setContainsAll(this, other);
-  }
-
-  Set<E> intersection(Set<E> other) {
-    return IterableMixinWorkaround.setIntersection(
-        this, other, new LinkedHashSet<E>());
-  }
-
-  Set<E> union(Set<E> other) {
-    return IterableMixinWorkaround.setUnion(
-        this, other, new LinkedHashSet<E>());
-  }
-
-  Set<E> difference(Set<E> other) {
-    return IterableMixinWorkaround.setDifference(
-        this, other, new LinkedHashSet<E>());
-  }
+  // Set interface from _SetMixin<E>.
+  Set<E> _newSet() => new LinkedHashSet<E>();
 
   String toString() => Collections.collectionToString(this);
 }