reactor: rename tokio-reactor -> tokio-net (#1450)

* reactor: rename tokio-reactor -> tokio-net

This is in preparation for #1264

ui-tests/tests/features.rs

@@ -1,9 +1,22 @@
 #[test]
-fn features() {
+#[cfg(feature = "tokio-with-net")]
+#[allow(unused_imports)]
+fn tokio_with_net() {
+    // Reactor is present
+    use ui_tests::tokio::reactor;
+
+    // net is present
+    use ui_tests::tokio::net;
+}
+#[test]
+fn compile_fail() {
     let t = trybuild::TestCases::new();
 
     #[cfg(feature = "executor-without-current-thread")]
     t.compile_fail("tests/ui/executor_without_current_thread.rs");
 
+    #[cfg(feature = "tokio-no-features")]
+    t.compile_fail("tests/ui/tokio_without_net_missing_reactor.rs");
+
     drop(t);
 }

ui-tests/tests/ui/tokio_without_net_missing_reactor.rs

@@ -0,0 +1,3 @@
+use ui_tests::tokio::reactor;
+
+fn main() {}

ui-tests/tests/ui/tokio_without_net_missing_reactor.stderr

@@ -0,0 +1,7 @@
+error[E0432]: unresolved import `ui_tests::tokio::reactor`
+ --> $DIR/tokio_without_net_missing_reactor.rs:1:5
+  |
+1 | use ui_tests::tokio::reactor;
+  |     ^^^^^^^^^^^^^^^^^^^^^^^^ no `reactor` in `tokio`
+
+For more information about this error, try `rustc --explain E0432`.