Revert "Fixing formatting of dart:html's dart2js annotations."

tools/dom/templates/html/impl/impl_MutationObserver.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 html;
-
-$(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
+$ANNOTATIONS
+@SupportedBrowser(SupportedBrowser.CHROME)
+@SupportedBrowser(SupportedBrowser.FIREFOX)
+@SupportedBrowser(SupportedBrowser.SAFARI)
+@Experimental()
+class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
 $!MEMBERS
   /**
    * Checks to see if the mutation observer API is supported on the current
    * platform.
    */
   static bool get supported {
 $if DARTIUM
     return true;
 $else
     return JS('bool',
@@ skipping 77 matching lines @@
     // Dummy statement to mark types as instantiated.
     JS('MutationObserver|MutationRecord', '0');
 
     return JS('MutationObserver',
         'new(window.MutationObserver||window.WebKitMutationObserver||'
         'window.MozMutationObserver)(#)',
         convertDartClosureToJS(callback, 2));
   }
 $endif
 }