fix parsing of semantic template interation w/ shadowdom polyfill

pkg/mdv/test/template_element_test.dart

 // Copyright (c) 2013, 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 template_element_test;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:html';
 import 'dart:math' as math;
@@ skipping 1100 matching lines @@
 
     var optgroup = select.nodes[1];
     expect(optgroup.nodes[0].tagName, 'TEMPLATE');
     expect(optgroup.nodes[1].tagName, 'OPTION');
     expect(optgroup.nodes[1].text, '0');
     expect(optgroup.nodes[2].tagName, 'OPTION');
     expect(optgroup.nodes[2].text, '1');
   });
 
   observeTest('NestedIterateTableMixedSemanticNative', () {
-    if (!TemplateElement.supported) return;

[justinfagnani, 2013/07/23 21:05:14]

Does TemplateElement.supported work properly? Does it need to be updated or
removed?

[Jennifer Messerly, 2013/07/23 21:09:32]

I think the issue is that Shadow DOM polyfill creates the appearance that the
HTMLTemplateElement is there, even though HTML parsing doesn't support
<template>. Maybe there should be another property "parsingSupported" or
something. But my understanding is all those properties are going away.

+    if (!parserHasNativeTemplate) return;
 
     var div = createTestHtml(
         '<table><tbody>'
           '<template repeat="{{}}">'
             '<tr>'
               '<td template repeat="{{}}" class="{{ val }}">{{ val }}</td>'
             '</tr>'
           '</template>'
         '</tbody></table>');
 
@@ skipping 607 matching lines @@
       k = k is String ? sym(k) : _deepToSymbol(k);
       result[k] = _deepToSymbol(v);
     });
     return result;
   }
   if (value is Iterable) {
     return value.map(_deepToSymbol).toList();
   }
   return value;
 }