Added method map to Collection interface and all its implementations (except classes generated fr...

corelib/src/implementation/hash_map_set.dart

Index: corelib/src/implementation/hash_map_set.dart
===================================================================
--- corelib/src/implementation/hash_map_set.dart	(revision 2973)
+++ corelib/src/implementation/hash_map_set.dart	(working copy)
@@ -336,6 +336,14 @@
     });
   }
 
+  Set map(f(E element)) {
+    Set result = new Set();
+    _backingMap.forEach(void _(E key, E value) {
+      result.add(f(key));
+    });
+    return result;
+  }
+
   Set<E> filter(bool f(E element)) {
     Set<E> result = new Set<E>();
     _backingMap.forEach(void _(E key, E value) {