Add basic_fetch and a skeleton http_fetch
Add a basic CORS Cache and a CORS Cache trait
Add a task-based CORS Cache
Some docs
Start using more typed units in the compositor

Now that rust-layers is starting to support typed units, we can use
them more thoroughly in the compositor. This is a step toward removing
as many untyped units as possible.
Transmute std::raw::TraitObject rather than (some) custom tuples/structs.

Context:
http://www.mail-archive.com/dev-servo@lists.mozilla.org/msg00867.html

This fixes the known issues, but there might be other places
where we do "bad" transmutes that I haven’t discovered.
Add a canvas create, break script’s dependency on gfx.

The build time on my laptop after touching gfx goes from 1m37s ot 46s.
Remove RenderListener::set_layer_clip_rect

It is currently unused.
Uppercase element.tagName for HTML elements only

Fixes #3146
Merge pull request #3147 from mbrubeck/tagname-upper

Uppercase element.tagName for HTML elements only r=Ms2ger
Merge pull request #3170 from SimonSapin/trait-object-transmute

Transmute std::raw::TraitObject rather than (some) custom tuples/structs
Support callback return types in codegen
Merge pull request #3141 from Manishearth/fetch-stuff

Some more Fetch and CORS Cache stuff; r=jdm
Merge pull request #3178 from SimonSapin/canvas-crate

Add a canvas create, break script’s dependency on gfx.
Disable same-origin.html for intermittent failures (fixes #3180).

We don't currently implement the same-origin restriction at all, so there's
little point in running this test.
Merge pull request #3184 from Ms2ger/disable-workers-same-origin-test

Disable same-origin.html for intermittent failures (fixes #3180).; r=jgraham
Merge pull request #3183 from ChrisParis/callback-return

Support callback return types in codegen
Make text decorations be independent display items.

The goal it to avoid having too much layout logic (which gets more complex in vertical text) in gfx code.
Implement sideways text.
Merge pull request #3181 from SimonSapin/sideways-text

Sideways text