Make Set.containsAll accept Iterable. Deprecate Set.isSubsetOf.

tools/dom/src/CssClassSet.dart

Index: tools/dom/src/CssClassSet.dart
diff --git a/tools/dom/src/CssClassSet.dart b/tools/dom/src/CssClassSet.dart
index c1ef6bbad732b83c338fd7d5e033464645e7a997..8d04493d596e0edb233c886290893911d2f27e45 100644
--- a/tools/dom/src/CssClassSet.dart
+++ b/tools/dom/src/CssClassSet.dart
@@ -105,12 +105,18 @@ abstract class CssClassSet implements Set<String> {
   bool isSubsetOf(Collection<String> collection) =>
     readClasses().isSubsetOf(collection);
 
-  bool containsAll(Collection<String> collection) =>
+  bool containsAll(Iterable<String> collection) =>
     readClasses().containsAll(collection);
 
   Set<String> intersection(Collection<String> other) =>
     readClasses().intersection(other);
 
+  Set<String> union(Collection<String> other) =>

[floitsch, 2013/03/14 11:33:50]

Set.

+    readClasses().union(other);
+
+  Set<String> difference(Collection<String> other) =>

[floitsch, 2013/03/14 11:33:50]

ditto.

+    readClasses().difference(other);
+
   String get first => readClasses().first;
   String get last => readClasses().last;
   String get single => readClasses().single;