Revert "appendHtml, when sanitizing, should create document fragment in the right context"

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

 // Copyright (c) 2012, 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;
 
 class _ChildrenElementList extends ListBase<Element>
     implements NodeListWrapper {
   // Raw Element.
   final Element _element;
@@ skipping 1019 matching lines @@
    * See also:
    *
    * * [insertAdjacentText]
    * * [insertAdjacentElement]
    */
   void insertAdjacentHtml(String where, String html, {NodeValidator validator,
       NodeTreeSanitizer treeSanitizer}) {
       if (treeSanitizer is _TrustedHtmlTreeSanitizer) {
         _insertAdjacentHtml(where, html);
       } else {
-        _insertAdjacentNode(where, createFragment(html,
+        _insertAdjacentNode(where, new DocumentFragment.html(html,
             validator: validator, treeSanitizer: treeSanitizer));
       }
   }
 
 $if DART2JS
 
   @JSName('insertAdjacentHTML')
   void _insertAdjacentHtml(String where, String text) native;
 
   /**
@@ skipping 277 matching lines @@
     if (_parseDocument == null) {
       _parseDocument = document.implementation.createHtmlDocument('');
       _parseRange = _parseDocument.createRange();
 
       // Workaround for Chrome bug 229142- URIs are not resolved in new doc.
       var base = _parseDocument.createElement('base');
       base.href = document.baseUri;
       _parseDocument.head.append(base);
     }
     var contextElement;
-    // Head and Area elements can't be used to create document fragments.
-    // Use the body instead.
-    if (this is BodyElement || _cannotBeUsedToCreateContextualFragment) {
+    if (this is BodyElement) {
       contextElement = _parseDocument.body;
     } else {
       contextElement = _parseDocument.createElement(tagName);
       _parseDocument.body.append(contextElement);
     }
     var fragment;
     if (Range.supportsCreateContextualFragment) {
       _parseRange.selectNodeContents(contextElement);
       fragment = _parseRange.createContextualFragment(html);
     } else {
       contextElement._innerHtml = html;
 
       fragment = _parseDocument.createDocumentFragment();
       while (contextElement.firstChild != null) {
         fragment.append(contextElement.firstChild);
       }
     }
     if (contextElement != _parseDocument.body) {
       contextElement.remove();
     }
 
     treeSanitizer.sanitizeTree(fragment);
     // Copy the fragment over to the main document (fix for 14184)
     document.adoptNode(fragment);
 
     return fragment;
   }
 
-  /** Test if createContextualFragment is supported for this element types */
-  bool get _cannotBeUsedToCreateContextualFragment =>
-      _tagsForWhichCreateContextualFragmentIsNotSupported.contains(tagName);
-
-  /**
-   * A hard-coded list of the tag names for which createContextualFragment
-   * isn't supported.
-   */
-  static const _tagsForWhichCreateContextualFragmentIsNotSupported =
-      const ['HEAD', 'AREA',
-      'BASE', 'BASEFONT', 'BR', 'COL', 'COLGROUP', 'EMBED', 'FRAME', 'FRAMESET',
-      'HR', 'IMAGE', 'IMG', 'INPUT', 'ISINDEX', 'LINK', 'META', 'PARAM',
-      'SOURCE', 'STYLE', 'TITLE', 'WBR'];
-
   /**
    * Parses the HTML fragment and sets it as the contents of this element.
    *
    * This uses the default sanitization behavior to sanitize the HTML fragment,
    * use [setInnerHtml] to override the default behavior.
    */
   void set innerHtml(String html) {
     this.setInnerHtml(html);
   }
 
@@ skipping 283 matching lines @@
   const ScrollAlignment._internal(this._value);
   toString() => 'ScrollAlignment.$_value';
 
   /// Attempt to align the element to the top of the scrollable area.
   static const TOP = const ScrollAlignment._internal('TOP');
   /// Attempt to center the element in the scrollable area.
   static const CENTER = const ScrollAlignment._internal('CENTER');
   /// Attempt to align the element to the bottom of the scrollable area.
   static const BOTTOM = const ScrollAlignment._internal('BOTTOM');
 }