mozilla-central modules for debugger detection

Borrows two python modules from mozilla-central to give mach the ability
to detect and pass arguments to a system's preferred debugger.

Links to borrowed files:
http://hg.mozilla.org/mozilla-central/file/c9cfa9b91dea/testing/mozbase/mozinfo/mozinfo/mozinfo.py
http://hg.mozilla.org/mozilla-central/file/c9cfa9b91dea/testing/mozbase/mozdebug/mozdebug/mozdebug.py
Adds --debug and --debugger flags to ./mach run
Panic if DOMTokenList#contains is called for an unparsed attribute.

Previously, if the attribute was not parsed into a token list, and the
tokens() method returned None, DOMTokenList#contains would silently return
false. This issue was encountered in
<https://github.com/servo/servo/pull/4076> and took quite some time to
figure out.
auto merge of #4083 : mttr/servo/mach_debugger_flag, r=mbrubeck

Borrows two python modules from mozilla-central to give mach the ability to detect and pass arguments to a system's preferred debugger, and adds `--debug` and `--debugger` flags to `./mach run`. This works almost like the functionality described [here](https://developer.mozilla.org/en-US/docs/Debugging_Mozilla_with_gdb), but at the moment it lacks a `--debugparams`  argument.

Links to borrowed files:
http://hg.mozilla.org/mozilla-central/file/c9cfa9b91dea/testing/mozbase/mozinfo/mozinfo/mozinfo.py
http://hg.mozilla.org/mozilla-central/file/c9cfa9b91dea/testing/mozbase/mozdebug/mozdebug/mozdebug.py
auto merge of #4084 : Ms2ger/servo/tokenlist-robust, r=jdm

Previously, if the attribute was not parsed into a token list, and the
tokens() method returned None, DOMTokenList#contains would silently return
false. This issue was encountered in
<https://github.com/servo/servo/pull/4076> and took quite some time to
figure out.
Lets `./mach test` infer testsuite from file

Usage Example:
```
$ ./mach test tests/wpt/web-platform-tests/dom/interfaces.html
 0:00.27 LOG: MainThread INFO Using 1 client processes
 ...
```

Note that while there is no functionality for `test-ref` to accept
individual files, `./mach test tests/ref` will still trigger `test-ref`.
auto merge of #4090 : mttr/servo/mach_infer_test, r=jdm

Fixes #4086

Lets `./mach test` take a file or directory as an argument, and infers `test-content`, `test-wpt`, or `test-ref` from the file's path. 

Usage Example:
```
$ ./mach test tests/wpt/web-platform-tests/dom/interfaces.html
 0:00.27 LOG: MainThread INFO Using 1 client processes
 ...
```
Note that while there is no functionality for `test-ref` to accept individual files, `./mach test tests/ref` will still trigger `test-ref`.

Passing arguments properly through python would have been ugly (though maybe there are some mach internals I could have taken advantage of), so this instead runs a new mach process and lets the individual test suites manage their arguments like normal.
Adds explicit --name argument to test-ref

In addition, `./mach test` will now take advantage of this when
inferring test suites from test files.
Implement a basic WebSocket interface.
Fix deprecation in selector matching test

The 'find' function was changed to 'get'. Changed to reflect this
warning given when running the tests.
auto merge of #4096 : servo/servo/websocket, r=Ms2ger

Closes #3813.
Add .cargo/config to .gitignore, move content to ports/android

This allows using .cargo/config at the root of the repository
for local path override, without risk of accidentally committing it.
auto merge of #4097 : orteipid/servo/fix_deprecation, r=SimonSapin

    selector_matching.rs:1263:44: 1263:63 warning: use of deprecated item: Renamed to `get`, #[warn(deprecated)] on by default
    selector_matching.rs:1263         assert_eq!(1, selector_map.id_hash.find(&atom!("top")).unwrap()[0].declarations.source_order);
                                                                         ^~~~~~~~~~~~~~~~~~~
    selector_matching.rs:1265:47: 1265:79 warning: use of deprecated item: Renamed to `get`, #[warn(deprecated)] on by default
    selector_matching.rs:1265         assert_eq!(0, selector_map.class_hash.find(&Atom::from_slice("intro")).unwrap()[0].declarations.source_order);
                                                                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    selector_matching.rs:1266:41: 1266:71 warning: use of deprecated item: Renamed to `get`, #[warn(deprecated)] on by default
    selector_matching.rs:1266         assert!(selector_map.class_hash.find(&Atom::from_slice("foo")).is_none());
                                                                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The 'find' function was changed to 'get'. Updated to remove this warning given when running the tests.
auto merge of #4099 : SimonSapin/servo/cargo-config, r=mbrubeck

This allows using `.cargo/config` at the root of the repository for local path override, without risk of accidentally committing it.

However I don’t have the environment to test the Android build. Would this break it?
fixes #4110, can input text without 'value' attribute present
Fix layout on google search results.
auto merge of #4113 : payload/servo/issue-4110, r=jdm

The attribute `value` and the underlying model `TextInput` are not connected to each other, so I just pulled the value out of `TextInput`.
auto merge of #4114 : glennw/servo/table-layout-fix, r=pcwalton
ports/cef: Use the CEF translator tool to generate the full set of CEF
bindings.

This replaces hand-implemented CEF bindings with proper Rust wrappers
automatically generated from the C++ headers. This means that, whenever
CEF's C++ headers change, we can easily generate both the appropriate C
API and the appropriate Rust API. It eliminates much of the hand-written
unsafe code within the CEF port, because the CEF translator tool now
knows how to generate Rust smart pointer wrappers for each class that
corrently perform reference counting.

Additionally, this commit adds utility macros (located in `macros.rs`)
that make it easier to correctly expose Rust objects as CEF objects.
They handle the marshaling of objects between Rust and CEF properly.
The net result of this is that you can write mostly-natural-looking Rust
in the CEF port and interact with it with a natural-looking C++ API on
the embedding side.

This setup relies on the branch of CEF located here:

    https://github.com/pcwalton/chromium-embedded-framework

To regenerate, follow the instructions in `ports/cef/README.md`. For
convenience, and because I don't anticipate the API to change much, I
have vendored in all of the appropriate interfaces.
Fixes for Linux.