Handle casts from Number to FutureOr<double>.

pkg/dev_compiler/test/browser/runtime_tests.js

 // 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.
 
 define(['dart_sdk'], function(dart_sdk) {
   const assert = chai.assert;
   const async = dart_sdk.async;
   const core = dart_sdk.core;
   const collection = dart_sdk.collection;
   const dart = dart_sdk.dart;
@@ skipping 114 matching lines @@
     let functionType = dart.functionType;
     let typedef = dart.typedef;
     let isSubtype = dart.isSubtype;
 
     let Object = core.Object;
     let String = core.String;
     let dynamic = dart.dynamic;
     let List = core.List;
     let Map = core.Map;
     let Map$ = core.Map$;
+    let double = core.double;
     let int = core.int;
     let num = core.num;
     let bool = core.bool;
 
     class A {}
     class B extends A {}
     class C extends B {}
 
     let AA$ = generic((T, U) => class AA extends core.Object {});
     let AA = AA$();
@@ skipping 131 matching lines @@
     test('String', () => {
       expect(isGroundType(String), true);
       expect(isGroundType(getReifiedType("foo")), true);
       checkType("foo", String);
       checkType("foo", Object);
       checkType("foo", dynamic);
 
       expect(cast(null, String), null);
     });
 
+    test('FutureOr', () => {
+      let FutureOr = async.FutureOr$;
+
+      assert.equal(dart.as(3, FutureOr(int)), 3);
+      assert.equal(dart.as(3, FutureOr(double)), 3);
+      assert.throws(() => dart.as(3.5, FutureOr(int)));
+      assert.equal(dart.as(3.5, FutureOr(double)), 3.5);
+      assert.isTrue(dart.is(3, FutureOr(int)));
+      assert.isTrue(dart.is(3, FutureOr(double)));
+      assert.isFalse(dart.is(3.5, FutureOr(int)));
+      assert.isTrue(dart.is(3.5, FutureOr(double)));
+    });
+
     test('Map', () => {
       let m1 = new (Map$(String, String))();
       let m2 = new (Map$(Object, Object))();
       let m3 = new Map();
       let m4 = new (collection.HashMap$(dart.dynamic, dart.dynamic))();
       let m5 = new collection.LinkedHashMap();
       let m6 = new (Map$(String, dart.dynamic))();
 
 
       expect(isGroundType(Map), true);
@@ skipping 927 matching lines @@
       list[0] = 42;
       assert.throws(() => list.add(42));
     });
 
     test('toString on ES Symbol', () => {
       let sym = Symbol('_foobar');
       assert.equal(dart.toString(sym), 'Symbol(_foobar)');
     });
   });
 });