Make getKeys, getValues getters (keys, values).

tests/html/utils.dart

 #library('TestUtils');
 
 /**
  * Verifies that [actual] has the same graph structure as [expected].
  * Detects cycles and DAG structure in Maps and Lists.
  */
 verifyGraph(expected, actual) {
   var eItems = [];
   var aItems = [];
 
@@ skipping 30 matching lines @@
       Expect.equals(expected.length, actual.length,
                     message(path, 'different list lengths'));
       for (var i = 0; i < expected.length; i++) {
         walk('$path[$i]', expected[i], actual[i]);
       }
       return;
     }
 
     if (expected is Map) {
       Expect.isTrue(actual is Map, message(path, '$actual is Map'));
-      for (var key in expected.getKeys()) {
+      for (var key in expected.keys) {
         if (!actual.containsKey(key)) {
           Expect.fail(message(path, 'missing key "$key"'));
         }
         walk('$path["$key"]',  expected[key], actual[key]);
       }
-      for (var key in actual.getKeys()) {
+      for (var key in actual.keys) {
         if (!expected.containsKey(key)) {
           Expect.fail(message(path, 'extra key "$key"'));
         }
       }
       return;
     }
 
     Expect.fail('Unhandled type: $expected');
   }
 
   walk('', expected, actual);
 }