Add language tests for Issue 18628.

tests/language/issue18628_1_test.dart

+// Copyright (c) 2014, 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 test checks for a regression found in Dart Editor: the
+// analyzer was treating [Type] as more specific than any type
+// variable (generic parameter).
+//
+// https://code.google.com/p/dart/issues/detail?id=18628
+
+class C<T> {
+  // This line is supposed to cause the warning; the other commented
+  // line just doesn't make sense without this line.
+  T t = int; /// 01: static type warning
+}
+
+main() {
+  C<Type> c = new C<Type>();
+  print(c.t); /// 01: static type warning
+}