Make it easier and more efficient to use trusted HTML text

tools/dom/src/Validators.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.
 
 part of dart.dom.html;
 
 
 /**
  * Interface used to validate that only accepted elements and attributes are
  * allowed while parsing HTML strings into DOM nodes.
@@ skipping 50 matching lines @@
       new _ValidatingTreeSanitizer(validator);
 
   /**
    * Called with the root of the tree which is to be sanitized.
    *
    * This method needs to walk the entire tree and either remove elements and
    * attributes which are not recognized as safe or throw an exception which
    * will mark the entire tree as unsafe.
    */
   void sanitizeTree(Node node);
+
+  /**
+   * A sanitizer for trees that we trust. It does no validation and allows
+   * any elements. It is also more efficient, since it can pass the text
+   * directly through to the underlying APIs without creating a document 
+   * fragment to be sanitized.
+   */
+  static const trusted = const _TrustedHtmlTreeSanitizer();
 }
 
 /**
+ * A sanitizer for trees that we trust. It does no validation and allows
+ * any elements.
+ */
+class _TrustedHtmlTreeSanitizer implements NodeTreeSanitizer {
+  const _TrustedHtmlTreeSanitizer();
+
+  sanitizeTree(Node node) {}
+}
+  
+/**
  * Defines the policy for what types of uris are allowed for particular
  * attribute values.
  *
  * This can be used to provide custom rules such as allowing all http:// URIs
  * for image attributes but only same-origin URIs for anchor tags.
  */
 abstract class UriPolicy {
   /**
    * Constructs the default UriPolicy which is to only allow Uris to the same
    * origin as the application was launched from.
@@ skipping 174 matching lines @@
       case Node.COMMENT_NODE:
       case Node.DOCUMENT_FRAGMENT_NODE:
       case Node.TEXT_NODE:
       case Node.CDATA_SECTION_NODE:
         break;
       default:
         _removeNode(node, parent);
     }
   }
 }