Fixes rust-lang#52774

Doing the expansion on onhashchange seems too late.

Fixes rust-lang#48726

Fixes rust-lang#49485 for section headings.

…-display, r=QuietMisdreavus

Improve unstable message display

Fixes rust-lang#51387.
Reopening of rust-lang#51563.

New display:

<img width="1440" alt="screen shot 2018-08-04 at 00 01 39" src="https://user-images.githubusercontent.com/3050060/43667793-dc14f708-9779-11e8-9808-f3ff126fc213.png">

r? @QuietMisdreavus

libtest terse format: show how far in we are

So for example `./x.py test src/libcore` looks like
```
running 881 tests
.................................................................................................... 100/881
.................................................................................................... 200/881
.................................................................................................... 300/881
.............................................................i.i.................................... 400/881
.................................................................................................... 500/881
.................................................................................................... 600/881
.................................................................................................... 700/881
.................................................................................................... 800/881
.................................................................................
test result: ok. 879 passed; 0 failed; 2 ignored; 0 measured; 0 filtered out
```
When I am waiting for 3500 ui tests to complete, I am often missing some sense of how far in these 3500 it is.

Getting the total count in `write_run_start` is a bit hacky; I did that to not change the "public interface" of the formatters. I can also give them an extra argument in their constructor so that they know from the beginning how many tests there will be. Would you prefer that? (I think I would, but I wanted to get feedback first.)

Automatically expand a section even after page load

Fixes rust-lang#52774

…ietMisdreavus

Add struct keyword doc

Slowly, one keyword at a time.

r? @QuietMisdreavus

…llaumeGomez

rustdoc: Fix gap on section anchor symbol when hovering.

Fixes rust-lang#49485 for section headings.