Modified unittest to use new argument syntax.

tests/html/css_rule_list_test.dart

 #library('CSSRuleListTest');
 #import('../../pkg/unittest/unittest.dart');
 #import('../../pkg/unittest/html_config.dart');
 #import('dart:html');
 
 main() {
 
+  var isCSSRuleList =
+      predicate((x) => x is List<CSSRule>, 'is a List<CSSRule>');
+
   useHtmlConfiguration();
 
   test("ClientRectList test", () {
     var sheet = document.styleSheets[0];
     List<CSSRule> rulesList = sheet.cssRules;
-    Expect.isTrue(rulesList is List<CSSRule>);
+    expect(rulesList, isCSSRuleList);
   });
 }