Handle synthetic nodes use to throw exceptions

pkg/compiler/lib/src/js_backend/no_such_method_registry.dart

 // Copyright (c) 2015, 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.
 
 import '../common.dart';
 import '../common/names.dart' show Identifiers, Names, Selectors;
 import '../compiler.dart' show Compiler;
 import '../elements/elements.dart';
 import '../tree/tree.dart';
 import 'backend.dart';
@@ skipping 249 matching lines @@
         body.statements.nodes.tail.isEmpty) {
       if (body.statements.nodes.head is ExpressionStatement) {
         ExpressionStatement stmt = body.statements.nodes.head;
         return stmt.expression is Throw;
       }
     }
     return false;
   }
 }
 
-enum NsmCategory { DEFAULT, THROWING, NOT_APPLICABLE, OTHER, }
+enum NsmCategory {
+  DEFAULT,
+  THROWING,
+  NOT_APPLICABLE,
+  OTHER,
+}