Reify implicit casts for FutureOr

pkg/analyzer/test/src/task/strong/checker_test.dart

Index: pkg/analyzer/test/src/task/strong/checker_test.dart
diff --git a/pkg/analyzer/test/src/task/strong/checker_test.dart b/pkg/analyzer/test/src/task/strong/checker_test.dart
index 4ac3e49b826f8e83da769e4ed2850a9a84ac4bc8..c6e7e4534beceb9a00dc43932a71dfcecbc8a60e 100644
--- a/pkg/analyzer/test/src/task/strong/checker_test.dart
+++ b/pkg/analyzer/test/src/task/strong/checker_test.dart
@@ -921,14 +921,14 @@ dynamic x;
 
 foo1() async => x;
 Future foo2() async => x;
-Future<int> foo3() async => x;
+Future<int> foo3() async => /*info:DYNAMIC_CAST*/x;
 Future<int> foo4() async => new Future<int>.value(x);
 Future<int> foo5() async =>
     /*error:RETURN_OF_INVALID_TYPE*/new Future<String>.value(x);
 
 bar1() async { return x; }
 Future bar2() async { return x; }
-Future<int> bar3() async { return x; }
+Future<int> bar3() async { return /*info:DYNAMIC_CAST*/x; }
 Future<int> bar4() async { return new Future<int>.value(x); }
 Future<int> bar5() async {
   return /*error:RETURN_OF_INVALID_TYPE*/new Future<String>.value(x);
@@ -955,7 +955,7 @@ Future<bool> get issue_ddc_264 async {
 
 
 Future<String> issue_sdk_26404() async {
-  return (1 > 0) ? new Future<String>.value('hello') : "world";
+  return (/*info:DOWN_CAST_COMPOSITE*/(1 > 0) ? new Future<String>.value('hello') : "world");

[vsm, 2017/04/05 15:52:59]

FYI - this is a cast from Object to FutureOr<String> :-(

[Leaf, 2017/04/05 20:47:27]

The fact that the LUB is Object is WAI.  The consensus on the language team was
not to make LUB produce FutureOr.

Treating this as a cast to FutureOr<String> is, I believe, a valid
implementation strategy but is not the only valid strategy.

[vsm, 2017/04/07 22:23:07]

Makes sense.  Yes, it'll work - just unnecessary casts.

 }
 ''');
   }