Create erroneous element when resolution of initializer fails.

dart/pkg/compiler/lib/src/enqueue.dart

Index: dart/pkg/compiler/lib/src/enqueue.dart
diff --git a/dart/pkg/compiler/lib/src/enqueue.dart b/dart/pkg/compiler/lib/src/enqueue.dart
index c2638b43a5d7c4614ad18ad30d4e461e8a36882c..9d04cd1e6b89654f0d3299f3d8a19b463056777a 100644
--- a/dart/pkg/compiler/lib/src/enqueue.dart
+++ b/dart/pkg/compiler/lib/src/enqueue.dart
@@ -697,6 +697,7 @@ class ResolutionEnqueuer extends Enqueuer {
   }
 
   bool internalAddToWorkList(Element element) {
+    if (element.isErroneous) return false;
     assert(invariant(element, element is AnalyzableElement,
         message: 'Element $element is not analyzable.'));
     if (hasBeenResolved(element)) return false;