Auto merge of #9149 - adrianheine:webFonts, r=glennw

Correctly handle local sources for CSS3 fonts

Currently, servo panics for me when loading something like this:

```
@font-face {
  font-family: "test family";
  src: local(test font face);
}
```

That's due to a bug in `FontCacheTask`. `FontCacheTask` tries to get the value for the key
"test font face" from `self.web_families`, but previously initialized a value for the key "test family".

These two commits add an awkward test and fix the bug by not shadowing the variable `family_name`. Since the argument to `local()` should explicitly not be the name of a font family, the previous variable name was wrong and misleading anyways.

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tests/unit/gfx/Cargo.toml

@@ -10,3 +10,9 @@ doctest = false
 
 [dependencies.gfx]
 path = "../../../components/gfx"
+
+[dependencies.ipc-channel]
+git = "https://github.com/servo/ipc-channel"
+
+[dependencies.style]
+path = "../../../components/style"

tests/unit/gfx/font_cache_task.rs

@@ -0,0 +1,21 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use gfx::font_cache_task::FontCacheTask;
+use ipc_channel::ipc;
+use style::computed_values::font_family::FontFamily;
+use style::font_face::Source;
+
+#[test]
+fn test_local_web_font() {
+  let (inp_chan, _) = ipc::channel().unwrap();
+  let (out_chan, out_receiver) = ipc::channel().unwrap();
+  let font_cache_task = FontCacheTask::new(inp_chan);
+  let family_name = FontFamily::FamilyName(From::from("test family"));
+  let variant_name = FontFamily::FamilyName(From::from("test font face"));
+
+  font_cache_task.add_web_font(family_name, Source::Local(variant_name), out_chan);
+
+  assert_eq!(out_receiver.recv().unwrap(), ());
+}

tests/unit/gfx/lib.rs

@@ -3,5 +3,8 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 extern crate gfx;
+extern crate ipc_channel;
+extern crate style;
 
+#[cfg(test)] mod font_cache_task;
 #[cfg(test)] mod text_util;