Bug 1319199 - Update webrender_bindings to opt-out of freetype. r=gfx?

Since webrender now re-exports the servo-freetype-sys option as a feature,
we can opt out of having that in webrender_bindings and use the webrender as
unmodified.

This patch also updates the README as the in-tree webrender is now exactly
the same as upstream webrender, which simplifies future updates to webrender.

MozReview-Commit-ID: 6JBtgjWIcn2

README.webrender

@@ -35,31 +35,21 @@ What if you have to make changes to webrender itself?
 
 1) Update your graphics branch checkout to the latest code on the
 graphics branch
-2) Separately, check out the webrender repo to the last version we
-used in-tree (right now it's
-git:b2a15e8b948a7c5db7f5fe7fbfa6fe4c8dda4a0b)
-3) Do a diff between the webrender repo and the stuff we have in-tree
-to see what the differences are and make a note. The only differences (if any)
-should be in the Cargo.toml file.
-4) Update the webrender repo to the version you want
-5) Copy over the webrender files into gfx/webrender (and
-gfx/webrender_traits) but make sure you keep the changes from step 3.
-6) Commit your changes to the graphics branch locally
-7) Run |mach vendor rust| to update the rust dependencies in third_party/rust
-8) Commit the vendored changes locally
-9) Build and test. You may need to make changes in bindings.rs or on
-the C++ side depending on what changed in webrender. This can
-potentially be quite tricky if you don't fully understand the API
-changes on the webrender side. In this step, try to not use your new
-features yet, just get the build working with the minimal changes.
-10) Update the git revision in this README.webrender file, step (2) above
-11) Commit the changes locally from step 9, and push everything to the
-graphics branch.
-12) Now you have an update webrender with the new features you wanted,
-so you can write gecko code against them.
+2) Check out and update the webrender repo to the version you want
+3) Copy over the webrender and webrender_traits folders into gfx/.
+4) If you need to modify webrender_bindings/Cargo.toml to include or remove
+   features, do so now.
+4) Commit your changes to the graphics branch locally
+5) Run |mach vendor rust| to update the rust dependencies in third_party/rust
+6) Commit the vendored changes locally
+7) Build and test. You may need to make changes in bindings.rs or on
+   the C++ side depending on what changed in webrender. This can
+   potentially be quite tricky if you don't fully understand the API
+   changes on the webrender side. In this step, try to not use your new
+   features yet, just get the build working with the minimal changes.
+8) Commit the changes locally from step 7, and push everything to the
+   graphics branch.
+9) Now you have an update webrender with the new features you wanted,
+   so you can write gecko code against them.
 
-Yes, this is very painful. Once we upstream all the webrender changes
-we have in our local tree, this will become simpler because it will remove
-step 2-3, and simplify step 5 to a copy. Step 9 is likely going to
-remain tricky if there are incompatible API changes on the WR side,
-hopefully those will be kept to a minimum.
+Yes, this is somewhat painful. It used to be worse. :)

gfx/webrender_bindings/Cargo.toml

@@ -5,12 +5,16 @@ authors = ["The Mozilla Project Developers"]
 license = "MPL-2.0"
 
 [dependencies]
-webrender = {path = "../webrender"}
 webrender_traits = {path = "../webrender_traits"}
 euclid = "0.10"
 app_units = "0.3"
 gleam = "0.2"
 
+[dependencies.webrender]
+path = "../webrender"
+default-features = false
+features = ["codegen"]
+
 [target.'cfg(target_os = "macos")'.dependencies]
 core-foundation = "0.2.2"