Add spacing between trait functions

[GuillaumeGomez]

Fixes #42988.

[rust-highfive]

Some changes occurred in HTML/CSS.

cc @GuillaumeGomez

[rust-highfive]

r? @frewsxcv

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[GuillaumeGomez]

r? @QuietMisdreavus

[QuietMisdreavus]

Something worth noting, is that the spacers you're adding are mechanically different from the one that's already there between the required methods and the provided ones. The existing spacer just printed an extra \n into the text, but the spacer you added is a div tag, using an entirely new CSS class. I'm not sure I care enough either way, but this new inconsistency caught my eye.

[QuietMisdreavus]

...also, travis ICE'd when running rustdoc, saying that it underflowed a subtraction.

[00:37:11] error: internal compiler error: unexpected panic
[00:37:11]
[00:37:11] note: the compiler unexpectedly panicked. this is a bug.
[00:37:11]
[00:37:11] note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
[00:37:11]
[00:37:11] note: rustc 1.20.0-dev (f08e9e8e8 2017-07-08) running on x86_64-unknown-linux-gnu
[00:37:11]
[00:37:11] thread 'rustc' panicked at 'attempt to subtract with overflow', /checkout/src/librustdoc/html/render.rs:2095:0
[00:37:11] note: Run with RUST_BACKTRACE=1 for a backtrace.
[00:37:11]
[00:37:11] error: Could not document collections.
[00:37:11]
[00:37:11] Caused by:
[00:37:11] process didn't exit successfully: /checkout/obj/build/bootstrap/debug/rustdoc --crate-name collections /checkout/src/libcollections/lib.rs --target x86_64-unknown-linux-gnu -o /checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/doc -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps -L dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/release/deps --extern alloc=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps/liballoc-de02a8fa7643706b.rlib --extern core=/checkout/obj/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps/libcore-ec524bba96280a11.rlib (exit code: 101)

[QuietMisdreavus]

From a conversation on IRC, imperio mentioned that the different mechanism is there to allow for different spacing within a section than between them. It's kinda subtle, but now that I know what it's for, I see it. r=me pending travis.

[QuietMisdreavus]

@bors r+

Thanks!

[bors]

📌 Commit 12dccbd has been approved by QuietMisdreavus

[bors]

⌛ Testing commit 12dccbd with merge 65cfc8f8c5e9d4e28e1392560005fa7a24cdf25d...

[GuillaumeGomez]

@bors: r=QuietMisdreavus

[bors]

💡 This pull request was already approved, no need to approve it again.

• This pull request is currently being tested. If there's no response from the continuous integration service, you may use retry to trigger a build again.

[bors]

📌 Commit 12dccbd has been approved by QuietMisdreavus

[bors]

⌛ Testing commit 12dccbd with merge 8b1271f...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: QuietMisdreavus
Pushing 8b1271f to master...