Expand ResolvedAst to handle synthetic constructors.

pkg/compiler/lib/src/deferred_load.dart

Index: pkg/compiler/lib/src/deferred_load.dart
diff --git a/pkg/compiler/lib/src/deferred_load.dart b/pkg/compiler/lib/src/deferred_load.dart
index 0d377aa41d10f8fdd4b0a386d0c80a959d420870..b8164aeec900424a2a57763d956f60fcc5501a4b 100644
--- a/pkg/compiler/lib/src/deferred_load.dart
+++ b/pkg/compiler/lib/src/deferred_load.dart
@@ -30,6 +30,7 @@ import 'elements/elements.dart'
         LocalFunctionElement,
         MetadataAnnotation,
         PrefixElement,
+        ResolvedAstKind,
         ScopeContainerElement,
         TypedefElement;
 import 'js_backend/js_backend.dart' show JavaScriptBackend;
@@ -337,6 +338,10 @@ class DeferredLoadTask extends CompilerTask {
             }),
             IMPACT_USE);
 
+        if (analyzableElement.resolvedAst.kind != ResolvedAstKind.PARSED) {
+          return;
+        }
+
         TreeElements treeElements = analyzableElement.resolvedAst.elements;
         assert(treeElements != null);