Remove Collection references.

tests/html/svgelement_test.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library SvgElementTest;
 import "package:expect/expect.dart";
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 import 'dart:svg' as svg;
 
 main() {
   useHtmlIndividualConfiguration();
 
   var isSvgSvgElement =
       predicate((x) => x is svg.SvgSvgElement, 'is a SvgSvgElement');
 
-  Collection<String> _nodeStrings(Collection<Node> input) {
+  List<String> _nodeStrings(Iterable<Node> input) {
     final out = new List<String>();
     for (Node n in input) {
       if (n is Element) {
         Element e = n;
         out.add(e.tagName);
       } else {
         out.add(n.text);
       }
     }
     return out;
@@ skipping 387 matching lines @@
       var el = new svg.CircleElement();
       var classes = el.classes;
       expect(el.classes.length, 0);
       classes.toggle('foo');
       expect(el.classes.length, 1);
       classes.toggle('foo');
       expect(el.classes.length, 0);
     });
   });
 }