Remove Glutin dependency for WebGL

[emilio]

Now we have mac support, and since android build is broken, we can
drop glutin from WebGL code.

Went back to upstream repo, see:
servo/surfman#1 (comment)

[highfive]

Thanks for the pull request, and welcome! The Servo team is excited to review your changes, and you should hear from @glennw (or someone else) soon.

[hoppipolla-critic-bot]

Critic review: https://critic.hoppipolla.co.uk/r/4919

This is an external review system which you may optionally use for the code review of your pull request.

In order to help critic track your changes, please do not make in-place history rewrites (e.g. via git rebase -i or git commit --amend) when updating this pull request.

[jdm]

-S-awaiting-review +S-needs-code-changes

---

Reviewed files:

• components/canvas/Cargo.toml @ r1
• components/canvas/lib.rs @ r1
• components/canvas/webgl_paint_task.rs @ r1
• components/servo/Cargo.lock @ r1
• ports/cef/Cargo.lock @ r1
• ports/gonk/Cargo.lock @ r1

---

^{components/canvas/webgl_paint_task.rs, line 208 [r1] (raw file):}
This comment seems addressed.

---

Comments from the review on Reviewable.io

[emilio]

^{components/canvas/webgl_paint_task.rs, line 208 [r1] (raw file):}
Done.

---

Comments from the review on Reviewable.io

[jdm]

@bors-servo: r+
-S-awaiting-review +S-awaiting-merge

---

Comments from the review on Reviewable.io

[bors-servo]

📌 Commit 6bef500 has been approved by jdm

[bors-servo]

⌛ Testing commit 6bef500 with merge a39b751...

[bors-servo]

💔 Test failed - mac2

[jdm]

/Users/servo/.cargo/git/checkouts/rust-offscreen-rendering-context-902f85b061901132/master/src/platform/with_cgl/native_gl_context.rs:47:16: 47:33 error: unresolved name `CGLDestroyContext`
/Users/servo/.cargo/git/checkouts/rust-offscreen-rendering-context-902f85b061901132/master/src/platform/with_cgl/native_gl_context.rs:47             if CGLDestroyContext(self.native_context) != 0 {
                                                                                                                                                        ^~~~~~~~~~~~~~~~~

This needs a update-cargo.

[bors-servo]

☔ The latest upstream changes (presumably #5968) made this pull request unmergeable. Please resolve the merge conflicts.

[jdm]

@bors-servo: r+

[bors-servo]

📌 Commit a3b0c10 has been approved by jdm

[bors-servo]

⌛ Testing commit a3b0c10 with merge c7608f7...

[bors-servo]

☀️ Test successful - android, gonk, linux1, linux2, mac1, mac2