Auto merge of #19350 - gterzian:ignore_aborted_responses_in_caching, r=jdm

Ignore aborted responses in caching

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@jdm @KiChjang @Manishearth Follow up on https://github.com/servo/servo/pull/18676 and https://github.com/servo/servo/pull/19274 to ignore aborted responses in caching.

I also found out the cache shouldn't return any response whose body is still in `ResponseBody::Receiving` mode, because that fails the assertion at https://github.com/servo/servo/blob/master/components/net/fetch/methods.rs#L438(we might want to add a channel as pat of the cached response later on to deal with this case). I only found out now because I needed the response from the server to trickle in so that it could be cached and aborted.

I copied the `http-cache.py` server from the wpt folder, and added a 'trickle' option, which is necessary to actually have a failing test with a cached but aborted request, it's now passing.

I also remove one unused import that slippled through previously.

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components/net_traits/response.rs

@@ -10,6 +10,7 @@ use hyper::status::StatusCode;
 use hyper_serde::Serde;
 use servo_url::ServoUrl;
 use std::sync::{Arc, Mutex};
+use std::sync::atomic::AtomicBool;
 
 /// [Response type](https://fetch.spec.whatwg.org/#concept-response-type)
 #[derive(Clone, Debug, Deserialize, MallocSizeOf, PartialEq, Serialize)]
@@ -113,7 +114,8 @@ pub struct Response {
     /// whether or not to try to return the internal_response when asked for actual_response
     pub return_internal: bool,
     /// https://fetch.spec.whatwg.org/#concept-response-aborted
-    pub aborted: bool,
+    #[ignore_malloc_size_of = "AtomicBool heap size undefined"]
+    pub aborted: Arc<AtomicBool>,
 }
 
 impl Response {
@@ -135,7 +137,7 @@ impl Response {
             location_url: None,
             internal_response: None,
             return_internal: true,
-            aborted: false,
+            aborted: Arc::new(AtomicBool::new(false)),
         }
     }
 
@@ -165,7 +167,7 @@ impl Response {
             location_url: None,
             internal_response: None,
             return_internal: true,
-            aborted: false,
+            aborted: Arc::new(AtomicBool::new(false)),
         }
     }