Remove ConstellationChan.

[Ms2ger]

Thank you for contributing to Servo! Please replace each [ ] by [X] when the step is complete, and replace __ with appropriate data:

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• ./mach test-tidy --faster does not report any errors
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It's a pointless abstraction that propagates the obsolete chan terminology,
swaps the order in which the sender and receiver are returned, and hides a
source of panics.

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This change is

[highfive]

Heads up! This PR modifies the following files:

• @asajeffrey: components/constellation/constellation.rs
• @KiChjang: components/script/dom/bindings/global.rs, components/script/layout_interface.rs, components/script/dom/window.rs, components/script_traits/lib.rs, components/script_traits/lib.rs, components/script/dom/document.rs, components/script/dom/htmllinkelement.rs, components/script/clipboard_provider.rs, components/script/dom/workerglobalscope.rs, components/script/dom/htmltextareaelement.rs, components/script/script_thread.rs, components/script/dom/htmlinputelement.rs, components/script/dom/htmlbodyelement.rs, components/script/dom/htmliframeelement.rs, components/script/dom/webglrenderingcontext.rs, components/script/dom/bindings/trace.rs, components/script/dom/canvasrenderingcontext2d.rs
• @emilio: components/script/dom/webglrenderingcontext.rs

[highfive]

Warning

• These commits modify gfx, layout, and script code, but no tests are modified. Please consider adding a test!

[asajeffrey]

Yes yes yes!

[asajeffrey]

Reviewed 24 of 24 files at r1.
Review status: all files reviewed at latest revision, 2 unresolved discussions.

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components/constellation/constellation.rs, line 327 [r1] (raw file):

    pub fn start(state: InitialConstellationState) -> Sender<FromCompositorMsg> {
        let (ipc_script_sender, ipc_script_receiver) =
            ipc::channel::<FromScriptMsg>().expect("ipc channel failure");

Do we need to provide the type arguments here? Can we not just use ipc::channel().expect("ipc channel failure")?

---

components/layout/layout_thread.rs, line 1084 [r1] (raw file):

                rw_data.constellation_chan
                       .send(ConstellationMsg::ViewportConstrained(self.id, constraints))
                       .unwrap();

This is so much cleaner, hooray!

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Comments from Reviewable

[highfive]

New code was committed to pull request.

[asajeffrey]

@bors-servo r+

[bors-servo]

📌 Commit cc2b2b5 has been approved by asajeffrey

[nox]

@bors-servo r-

Homu confused, will r+ again.

[nox]

@bors-servo r=asajeffrey

[bors-servo]

📌 Commit cc2b2b5 has been approved by asajeffrey

[bors-servo]

⌛ Testing commit cc2b2b5 with merge 27c25e8...

[bors-servo]

☀️ Test successful - android, arm32, arm64, linux-dev, linux-rel, mac-dev-unit, mac-rel-css, mac-rel-wpt, windows