Add regression tests for issues rust-lang#18655 and rust-lang#18988.

Closes rust-lang#18655.
Closes rust-lang#18988.

Author: Nick Hamann

src/test/run-pass/issue-18655.rs

@@ -0,0 +1,31 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+trait Factory {
+    type Product;
+    fn create(&self) -> <Self as Factory>::Product;
+}
+
+impl Factory for f64 {
+    type Product = f64;
+    fn create(&self) -> f64 { *self * *self }
+}
+
+impl<A: Factory, B: Factory> Factory for (A, B) {
+    type Product = (<A as Factory>::Product, <B as Factory>::Product);
+    fn create(&self) -> (<A as Factory>::Product, <B as Factory>::Product) {
+        let (ref a, ref b) = *self;
+        (a.create(), b.create())
+    }
+}
+
+fn main() {
+    assert_eq!((16., 25.), (4., 5.).create());
+}

src/test/run-pass/issue-18988.rs

@@ -0,0 +1,19 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+pub trait Foo : Send { }
+
+pub struct MyFoo {
+    children: Vec<Box<Foo>>,
+}
+
+impl Foo for MyFoo { }
+
+pub fn main() { }