Add runtime tests for ignored checks

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;
   const dartx = dart.dartx;
 
+  dart.trapRuntimeErrors(false);
+
+  suite('ignore', () => {
+    "use strict";
+
+    let FutureOr = async.FutureOr$;
+    let Future = async.Future$;
+    let List = core.List$;
+
+    setup(() => {
+      dart_sdk.dart.ignoreWhitelistedErrors(false);
+    });
+
+    teardown(() => {
+      dart_sdk.dart.ignoreWhitelistedErrors(false);
+    });
+
+    test('FutureOr', () => {
+      let f = Future(dart.dynamic).value(42);
+      let l = [1, 2, 3];
+
+      assert.throws(() => { dart.as(f, FutureOr(core.int)); });
+      assert.throws(() => { dart.as(l, FutureOr(List(core.int)))});
+
+      dart_sdk.dart.ignoreWhitelistedErrors(true);
+      assert.equal(f, dart.as(f, FutureOr(core.int)));
+      assert.equal(l, dart.as(l, FutureOr(List(core.int))));
+    });
+  });
 
   suite('generic', () => {
     "use strict";
 
     let generic = dart.generic;
 
     test('zero arguments is not allowed', () => {
       assert.throws(() => { generic(function(){}); });
     });
 
@@ skipping 1218 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)');
     });
   });
 });