Adding supported check for HTML imports.

tools/dom/templates/html/impl/impl_HTMLLinkElement.darttemplate

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2014, 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.
 
 part of $LIBRARYNAME;
 
 @DocsEditable()
 $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$MIXINS$IMPLEMENTS$NATIVESPEC {
 $!MEMBERS
 
-  DataTransferItem operator[] (int index) {
+    /// Checks if HTML imports are supported on the current platform.
+  bool get supportsImport {
 $if DART2JS
-    return JS('DataTransferItem', '#[#]', this, index);
+    return JS('bool', '("import" in #)', this);
 $else
-    return __getter__(index);
+    return true;
 $endif
   }
-
 }