Fix crash when deferred loading would encounter an unresolved super setter.

pkg/compiler/lib/src/deferred_load.dart

 // Copyright (c) 2014, 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.
 
 library deferred_load;
 
 import 'common/backend_api.dart' show
     Backend;
 import 'common/tasks.dart' show
     CompilerTask;
@@ skipping 228 matching lines @@
   /// Finds all elements and constants that [element] depends directly on.
   /// (not the transitive closure.)
   ///
   /// Adds the results to [elements] and [constants].
   void _collectAllElementsAndConstantsResolvedFrom(
       Element element,
       Set<Element> elements,
       Set<ConstantValue> constants,
       isMirrorUsage) {
 
+    if (element.isErroneous) {
+      // Erroneous elements are ignored.
+      return;
+    }
+
     /// Recursively collects all the dependencies of [type].
     void collectTypeDependencies(DartType type) {
       if (type is GenericType) {
         type.typeArguments.forEach(collectTypeDependencies);
       }
       if (type is FunctionType) {
         for (DartType argumentType in type.parameterTypes) {
           collectTypeDependencies(argumentType);
         }
         for (DartType argumentType in type.optionalParameterTypes) {
@@ skipping 625 matching lines @@
         _importingLibrary = importingLibrary;
 
   String get importingLibraryName {
     String libraryName = _importingLibrary.getLibraryName();
     return libraryName == ""
       ? "<unnamed>"
       : libraryName;
   }
 
 }