Auto merge of #11196 - fduraffourg:master, r=jdm

Add unit tests for cookies handling

Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data:
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #9965

Either:
- [X] There are tests for these changes OR
- [ ] These changes do not require tests because _____

Add unit tests for the `net` component about cookies. The tests are generated
with a new `mach update-net-cookies` command from this repo: https://github.com/abarth/http-state.

This PR also includes two trivial bug fixes about cookie handling.

From all the tests included, the following ones are currently failing:

- cookie_http_state::test_0003
- cookie_http_state::test_0006
- cookie_http_state::test_attribute0004
- cookie_http_state::test_attribute0005
- cookie_http_state::test_attribute0007
- cookie_http_state::test_attribute0008
- cookie_http_state::test_domain0017
- cookie_http_state::test_mozilla0001
- cookie_http_state::test_mozilla0002
- cookie_http_state::test_mozilla0003
- cookie_http_state::test_mozilla0005
- cookie_http_state::test_mozilla0007
- cookie_http_state::test_mozilla0009
- cookie_http_state::test_mozilla0010
- cookie_http_state::test_mozilla0013

`test_000[36]` and `test_mozilla*` are failing because there is currently no
method to clean a `net::cookie_storage` from expired cookies.

`test_attribute000[4578]` are failing because hyper does not parse the `Secure`
attribute correctly. I will open an issue on the upstream project.

`test_domain0017` fails because the TLD .org is not on the PUB_DOMAINS list.

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components/net/cookie_storage.rs

@@ -57,10 +57,6 @@ impl CookieStorage {
             return;
         }
 
-        if cookie.cookie.value.is_empty() {
-            return;
-        }
-
         // Step 11
         if let Some(old_cookie) = old_cookie.unwrap() {
             // Step 11.3
@@ -107,7 +103,7 @@ impl CookieStorage {
             // Step 4
             (match acc.len() {
                 0 => acc,
-                _ => acc + ";"
+                _ => acc + "; "
             }) + &c.cookie.name + "=" + &c.cookie.value
         };
         let result = url_cookies.iter_mut().fold("".to_owned(), reducer);