Auto merge of #55707 - GuillaumeGomez:file-sidebar, r=QuietMisdreavus

Add source file sidebar

This is just a start currently but that gives a good overview of what it'll look like:

<img width="1440" alt="screenshot 2018-11-06 at 01 39 15" src="https://user-images.githubusercontent.com/3050060/48035592-05336180-e165-11e8-82e1-5ead0c345eb9.png">

r? @QuietMisdreavus

1 files changed, 15 insertions, 0 deletions

diff --git a/src/test/rustdoc/source-file.rs b/src/test/rustdoc/source-file.rs
new file mode 100644
index 00000000000..077817bcf5b
--- /dev/null
+++ b/src/test/rustdoc/source-file.rs
@@ -0,0 +1,15 @@
+// Copyright 2018 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.
+
+#![crate_name = "foo"]
+
+// @has source-files.js source-file.rs
+
+pub struct Foo;