Add type inference for assert statements.

pkg/front_end/testcases/inference/assert.dart

Index: pkg/front_end/testcases/inference/assert.dart
diff --git a/pkg/front_end/testcases/inference/assert.dart b/pkg/front_end/testcases/inference/assert.dart
new file mode 100644
index 0000000000000000000000000000000000000000..b1d500fcdb2e0fb3874c60c1a19f5b759ff90dfa
--- /dev/null
+++ b/pkg/front_end/testcases/inference/assert.dart
@@ -0,0 +1,15 @@
+// Copyright (c) 2017, 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.
+
+/*@testedFeatures=inference*/
+library test;
+
+T f<T>() => null;
+
+void test() {
+  assert(/*@typeArgs=dynamic*/ f());
+  assert(/*@typeArgs=dynamic*/ f(), /*@typeArgs=dynamic*/ f());
+}
+
+main() {}