Abort tracing in type inference in the presence of await.

pkg/compiler/lib/src/inferrer/node_tracer.dart

 // Copyright (c) 2013, 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.
 
 part of type_graph_inferrer;
 
 // A set of selectors we know do not escape the elements inside the
 // list.
 Set<String> doesNotEscapeListSet = new Set<String>.from(
   const <String>[
@@ skipping 126 matching lines @@
     }
   }
 
   void bailout(String reason) {
     if (_VERBOSE) {
       print('Bailing out on $tracedType because: $reason');
     }
     continueAnalyzing = false;
   }
 
+  void visitAwaitTypeInformation(AwaitTypeInformation info) {
+    bailout("Passed through await");
+  }
+
   void visitNarrowTypeInformation(NarrowTypeInformation info) {
     addNewEscapeInformation(info);
   }
 
   void visitPhiElementTypeInformation(PhiElementTypeInformation info) {
     addNewEscapeInformation(info);
   }
 
   void visitElementInContainerTypeInformation(
       ElementInContainerTypeInformation info) {
@@ skipping 229 matching lines @@
     }
     if (isParameterOfListAddingMethod(info.element) ||
         isParameterOfMapAddingMethod(info.element)) {
       // These elements are being handled in
       // [visitDynamicCallSiteTypeInformation].
       return;
     }
     addNewEscapeInformation(info);
   }
 }