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

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index cc559ea315716c1da91f05c9f0ebf44e86732b90..fa27d0d2b71cbe54b265eb70988b6bcab64da585 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -30179,12 +30179,18 @@ 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) =>
+    readClasses().union(other);
+
+  Set<String> difference(Collection<String> other) =>
+    readClasses().difference(other);
+
   String get first => readClasses().first;
   String get last => readClasses().last;
   String get single => readClasses().single;