Reapply 12799.

lib/html/src/dart2js_Conversions.dart

 // 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.
 
 
 // Conversions for IDBKey.
 //
 // Per http://www.w3.org/TR/IndexedDB/#key-construct
 //
 // "A value is said to be a valid key if it is one of the following types: Array
@@ skipping 187 matching lines @@
     if (e is File) {
       throw const NotImplementedException('structured clone of File');
     }
 
     if (e is _BlobImpl) return e;
     if (e is Blob) {
       throw const NotImplementedException('structured clone of Blob');
     }
 
     if (e is _FileListImpl) return e;
-    if (e is FileList) {
-      throw const NotImplementedException('structured clone of FileList');
-    }
 
     // TODO(sra): Firefox: How to convert _TypedImageData on the other end?
     if (e is _ImageDataImpl) return e;
     if (e is ImageData) {
-      throw const NotImplementedException('structured clone of FileList');
+      throw const NotImplementedException('structured clone of ImageData');
     }
 
     if (e is _ArrayBufferImpl) return e;
     if (e is ArrayBuffer) {
       throw const NotImplementedException('structured clone of ArrayBuffer');
     }
 
     if (e is _ArrayBufferViewImpl) return e;
     if (e is ArrayBufferView) {
       throw const NotImplementedException('structured clone of ArrayBufferView');
@@ skipping 162 matching lines @@
 }
 
 
 bool _isJavaScriptDate(value) => JS('bool', '# instanceof Date', value);
 bool _isJavaScriptRegExp(value) => JS('bool', '# instanceof RegExp', value);
 bool _isJavaScriptArray(value) => JS('bool', '# instanceof Array', value);
 bool _isJavaScriptSimpleObject(value) =>
     JS('bool', 'Object.getPrototypeOf(#) === Object.prototype', value);
 bool _isImmutableJavaScriptArray(value) =>
     JS('bool', @'!!(#.immutable$list)', value);