Fix for events not firing on sanitized elements

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index e519022dab9ba2eb9fe3453b3e995683a7f714b6..211b1e9bc59a7fe113e5aabb26db2f7f46aaaee0 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -9280,7 +9280,7 @@ abstract class Element extends Node implements ParentNode, ChildNode native "Ele
   ElementList querySelectorAll(String selectors) =>
     new _FrozenElementList._wrap(_querySelectorAll(selectors));
 
-  /** 
+  /**
    * Alias for [querySelector]. Note this function is deprecated because its
    * semantics will be changing in the future.
    */
@@ -9289,7 +9289,7 @@ abstract class Element extends Node implements ParentNode, ChildNode native "Ele
   @Experimental()
   Element query(String relativeSelectors) => querySelector(relativeSelectors);
 
-  /** 
+  /**
    * Alias for [querySelectorAll]. Note this function is deprecated because its
    * semantics will be changing in the future.
    */
@@ -10012,6 +10012,9 @@ abstract class Element extends Node implements ParentNode, ChildNode native "Ele
     }
 
     treeSanitizer.sanitizeTree(fragment);
+    // Copy the fragment over to the main document (fix for 14184)
+    document.adoptNode(fragment);
+
     return fragment;
   }