Make isEmpty a getter.

samples/third_party/dromaeo/tests/dom-query-htmlidiomatic.dart

 #library("dom_query_html");
 #import("dart:html");
 #import('../common/common.dart');
 #import("dart:math", prefix: "Math");
 #source("Common.dart");
 #source("RunnerSuite.dart");
 
 void main() {
   final int num = 40;
 
@@ skipping 58 matching lines @@
     })
     .test('getElementsByTagName(*)', () {
       for (int i = 0; i < num; i++) {
         List<Element> elems = document.queryAll('*');
         ret = elems.last().$dom_nodeType;
       }
     })
     .test('getElementsByTagName (not in document)', () {
       for (int i = 0; i < num; i++) {
         List<Element> elems = document.queryAll('strong');
-        ret = elems.isEmpty();
+        ret = elems.isEmpty;
       }
     })
     .test('getElementsByName', () {
       for (int i = 0; i < num * 20; i++) {
         List<Element> elems = document.queryAll('[name="test$num"]');
         ret = elems.last().$dom_nodeType;
         elems = document.queryAll('[name="test$num"]');
         ret = elems.last().$dom_nodeType;
         elems = document.queryAll('[name="test$num"]');
         ret = elems.last().$dom_nodeType;
         elems = document.queryAll('[name="test$num"]');
         ret = elems.last().$dom_nodeType;
       }
     })
     .test('getElementsByName (not in document)', () {
       for (int i = 0; i < num * 20; i++) {
         ret = document.queryAll('[name="test"]').length == 0;
         ret = document.queryAll('[name="test"]').length == 0;
         ret = document.queryAll('[name="test"]').length == 0;
         ret = document.queryAll('[name="test"]').length == 0;
         ret = document.queryAll('[name="test"]').length == 0;
       }
     })
     .end();
 }