Handle casts from Number to FutureOr<double>.

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/operations.dart

 // Copyright (c) 2015, 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.
 
 /// This library defines runtime operations on objects used by the code
 /// generator.
 part of dart._runtime;
 
 class InvocationImpl extends Invocation {
   final Symbol memberName;
@@ skipping 478 matching lines @@
 /// Returns false if [obj] is not an instance of [type] in both spec
 ///  and strong mode
 /// Returns null if [obj] is not an instance of [type] in strong mode
 ///  but might be in spec mode
 bool strongInstanceOf(obj, type, ignoreFromWhiteList) => JS(
     '',
     '''(() => {
   let actual = $getReifiedType($obj);
   let result = $isSubtype(actual, $type);
   if (result || actual == $jsobject ||
-      actual == $int && type == $double) return true;
+      actual == $int && type == $double ||
+      (actual == $int && $_isFutureOr(type)

[vsm, 2017/03/23 19:37:44]

Can type be FutureOr<FutureOr<T>> ?

Would something like

actual == $int && $isSubtype(double, $type)

make sense?

[Leaf, 2017/03/23 20:27:31]

Good idea, done.

+       && $getGenericArgs(type)[0] == $double)) {
+    return true;
+  }
   if (result === false) return false;
   if (!$_ignoreWhitelistedErrors || ($ignoreFromWhiteList == void 0)) return result;
   if ($_ignoreTypeFailure(actual, $type)) return true;
   return result;
 })()''');
 
 /// Returns true if [obj] is null or an instance of [type]
 /// Returns false if [obj] is non-null and not an instance of [type]
 /// in strong mode
 instanceOfOrNull(obj, type) => JS(
@@ skipping 465 matching lines @@
     name = '+' + name;
   }
   return name;
 }
 
 /// Emulates the implicit "loadLibrary" function provided by a deferred library.
 ///
 /// Libraries are not actually deferred in DDC, so this just returns a future
 /// that completes immediately.
 Future loadLibrary() => new Future.value();