Don't use ".catch" in dart2js generated code.

sdk/lib/html/html_common/conversions_dart2js.dart

Index: sdk/lib/html/html_common/conversions_dart2js.dart
diff --git a/sdk/lib/html/html_common/conversions_dart2js.dart b/sdk/lib/html/html_common/conversions_dart2js.dart
index 3b3a8adf3960f50b75bda109d7907acb1a2bd577..b7f3d7cbbccfd7604bb0b754bdbab6a95468147a 100644
--- a/sdk/lib/html/html_common/conversions_dart2js.dart
+++ b/sdk/lib/html/html_common/conversions_dart2js.dart
@@ -88,7 +88,7 @@ Future convertNativePromiseToDartFuture(promise) {
   var completer = new Completer();
   var then = convertDartClosureToJS((result) => completer.complete(result), 1);
   var error = convertDartClosureToJS((result) => completer.completeError(result), 1);
-  var newPromise = JS('', '#.then(#).catch(#)', promise, then, error);
+  var newPromise = JS('', '#.then(#)["catch"](#)', promise, then, error);
   return completer.future;
 }