Some janitoring over the layout crate

[nox]

This PR moves a bunch of code around and makes some methods from one-use traits into inherent methods.

---

This change is 

[highfive]

Heads up! This PR modifies the following files:

• @asajeffrey: components/script/dom/bindings/trace.rs, components/script/script_thread.rs, components/script/dom/window.rs
• @KiChjang: components/script/dom/bindings/trace.rs, components/script/script_thread.rs, components/script/dom/window.rs
• @emilio: components/layout/table_caption.rs, components/layout/table.rs, components/layout/display_list/builder.rs, components/layout/table_wrapper.rs, components/layout/table_rowgroup.rs and 7 more

[highfive]

Warning

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

[nox]

r? @SimonSapin

[emilio]

We have the URL here so reporting it should be trivial, mind filing an issue for that?

[nox]

I drive-by fixed it.

[emilio]

can you do instead:

let abspos_containing_block = established_reference_frame.is_some() || ....;
if abspos_containing_block {

[emilio]

And same here?

This looks wrong btw, an inline can also establish a reference frame.

[nox]

Want me to file a follow-up issue? This is just the same code as before right?

[emilio]

Oh, this is fancy.

[emilio]

You could also just move it to style, your call.

In any case I think this is simpler to read as follows, if you want to make that change:

let ui = values.get_inherited_ui();
if ui.pointer_events == PointerEvents::None {
    return None;
}

match ui.cursor {
    // ...
}

[nox]

Made some changes like you suggested but didn't move it to style given there is no other user.

[CYBAI]

From Travis 👀

Diff in /home/travis/build/servo/servo/components/script/dom/window.rs at line 1602:
     }
 
     pub fn scroll_offset_query(&self, node: &Node) -> Vector2D<f32> {
-        if let Some(scroll_offset) = self
-            .scroll_offsets
-            .borrow()
-            .get(&node.to_opaque())
-        {
+        if let Some(scroll_offset) = self.scroll_offsets.borrow().get(&node.to_opaque()) {
             return *scroll_offset;
         }
         Vector2D::new(0.0, 0.0)
Diff in /home/travis/build/servo/servo/components/script/dom/window.rs at line 1621:
         // The scroll offsets are immediatly updated since later calls
         // to topScroll and others may access the properties before
         // webrender has a chance to update the offsets.
-        self.scroll_offsets.borrow_mut().insert(
-            node.to_opaque(),
-            Vector2D::new(x_ as f32, y_ as f32),
-        );
+        self.scroll_offsets
+            .borrow_mut()
+            .insert(node.to_opaque(), Vector2D::new(x_ as f32, y_ as f32));
 
         let NodeScrollIdResponse(scroll_id) = self.layout_rpc.node_scroll_id();
 
Run `./mach fmt` to fix the formatting

[SimonSapin]

No need to change this back, but in the 2018 edition you can remove & from most patterns without adding * in the matched expression.

[nox]

@bors-servo r=emilio,SimonSapin

[bors-servo]

📌 Commit cf15336 has been approved by emilio,SimonSapin

[bors-servo]

⌛️ Testing commit cf15336 with merge c242abd...

[bors-servo]

☀️ Test successful - android-mac, arm32, arm64, linux-rel-css, linux-rel-wpt, mac-rel-css1, mac-rel-css2, mac-rel-wpt1, mac-rel-wpt2, mac-rel-wpt3, mac-rel-wpt4, magicleap, status-taskcluster
Approved by: emilio,SimonSapin
Pushing c242abd to master...