improve static type analysis for `await for`

pkg/analyzer/lib/src/task/strong/rules.dart

Index: pkg/analyzer/lib/src/task/strong/rules.dart
diff --git a/pkg/analyzer/lib/src/task/strong/rules.dart b/pkg/analyzer/lib/src/task/strong/rules.dart
index 3cd6db2a6875935017079a8d1dbf7c4445e32f4d..4ec540a724cccd2d63feb380652b2006b6334c01 100644
--- a/pkg/analyzer/lib/src/task/strong/rules.dart
+++ b/pkg/analyzer/lib/src/task/strong/rules.dart
@@ -57,10 +57,8 @@ class TypeRules {
   /// return null.
   FunctionType getCallMethodType(DartType t) {
     if (t is InterfaceType) {
-      ClassElement element = t.element;
-      InheritanceManager manager = new InheritanceManager(element.library);
-      FunctionType callType = manager.lookupMemberType(t, "call");
-      return callType;
+      MethodElement callMethod = t.lookUpMethod("call", null);
+      return callMethod != null ? callMethod.type : null;

[Paul Berry, 2015/10/29 16:29:59]

Similar nit here.

     }
     return null;
   }