Auto merge of #25687 - pshaughn:taintfile, r=jdm

Filter file: and about: responses opaquely

<!-- Please describe your changes on the following line: -->
file: and about: schemes were being treated like data: for cors purposes, when in fact they should have been subject to opaque response filtering. A comment indicated that this was necessary for some CSS tests, but I think the comment was out of date; the only tests depending on the unfiltered responses are unit tests that do not test any CSS functionality. I've updated those tests to now test for the opaque-filtering itself.

---
<!-- 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 #25686

<!-- Either: -->
- [X] There are tests for these changes, but also some loss of unit test coverage (#25693) and a newly failing test case (#25692)

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5 files changed, 29 insertions, 67 deletions

diff --git a/components/net/fetch/methods.rs b/components/net/fetch/methods.rs
index 101cf467444..e8c35e4a901 100644
--- a/components/net/fetch/methods.rs
+++ b/components/net/fetch/methods.rs
@@ -279,14 +279,7 @@ pub fn main_fetch(
             false
         };
 
-        if (same_origin && !cors_flag ) ||
-            current_url.scheme() == "data" ||
-            current_url.scheme() == "file" || // FIXME: Fetch spec has already dropped filtering against file:
-                                              //        and about: schemes, but CSS tests will break on loading Ahem
-                                              //        since we load them through a file: URL.
-            current_url.scheme() == "about" ||
-            request.mode == RequestMode::Navigate
-        {
+        if (same_origin && !cors_flag) || current_url.scheme() == "data" {
             // Substep 1.
             request.response_tainting = ResponseTainting::Basic;
 
diff --git a/components/net/tests/fetch.rs b/components/net/tests/fetch.rs
index d26343684f0..eddd8f67779 100644
--- a/components/net/tests/fetch.rs
+++ b/components/net/tests/fetch.rs
@@ -113,12 +113,21 @@ fn test_fetch_aboutblank() {
     let origin = Origin::Origin(url.origin());
     let mut request = Request::new(url, Some(origin), None);
     request.referrer = Referrer::NoReferrer;
+
     let fetch_response = fetch(&mut request, None);
+    // We should see an opaque-filtered response.
+    assert_eq!(fetch_response.response_type, ResponseType::Opaque);
     assert!(!fetch_response.is_network_error());
-    assert_eq!(
-        *fetch_response.body.lock().unwrap(),
-        ResponseBody::Done(vec![])
-    );
+    assert_eq!(fetch_response.headers.len(), 0);
+    let resp_body = fetch_response.body.lock().unwrap();
+    assert_eq!(*resp_body, ResponseBody::Empty);
+
+    // The underlying response behind the filter should
+    // have a 0-byte body.
+    let actual_response = fetch_response.actual_response();
+    assert!(!actual_response.is_network_error());
+    let resp_body = actual_response.body.lock().unwrap();
+    assert_eq!(*resp_body, ResponseBody::Done(vec![]));
 }
 
 #[test]
@@ -176,7 +185,6 @@ fn test_fetch_blob() {
     methods::fetch(&mut request, &mut target, &context);
 
     let fetch_response = receiver.recv().unwrap();
-
     assert!(!fetch_response.is_network_error());
 
     assert_eq!(fetch_response.headers.len(), 2);
@@ -198,25 +206,36 @@ fn test_fetch_blob() {
 }
 
 #[test]
-fn test_fetch_file() {
+fn test_file() {
     let path = Path::new("../../resources/servo.css")
         .canonicalize()
         .unwrap();
     let url = ServoUrl::from_file_path(path.clone()).unwrap();
+
     let origin = Origin::Origin(url.origin());
     let mut request = Request::new(url, Some(origin), None);
 
     let fetch_response = fetch(&mut request, None);
+    // We should see an opaque-filtered response.
+    assert_eq!(fetch_response.response_type, ResponseType::Opaque);
     assert!(!fetch_response.is_network_error());
-    assert_eq!(fetch_response.headers.len(), 1);
-    let content_type: Mime = fetch_response
+    assert_eq!(fetch_response.headers.len(), 0);
+    let resp_body = fetch_response.body.lock().unwrap();
+    assert_eq!(*resp_body, ResponseBody::Empty);
+
+    // The underlying response behind the filter should
+    // have the file's MIME type and contents.
+    let actual_response = fetch_response.actual_response();
+    assert!(!actual_response.is_network_error());
+    assert_eq!(actual_response.headers.len(), 1);
+    let content_type: Mime = actual_response
         .headers
         .typed_get::<ContentType>()
         .unwrap()
         .into();
     assert_eq!(content_type, mime::TEXT_CSS);
 
-    let resp_body = fetch_response.body.lock().unwrap();
+    let resp_body = actual_response.body.lock().unwrap();
     let file = fs::read(path).unwrap();
 
     match *resp_body {
diff --git a/tests/wpt/metadata/fetch/api/basic/scheme-about.any.js.ini b/tests/wpt/metadata/fetch/api/basic/scheme-about.any.js.ini
deleted file mode 100644
index e070826dde4..00000000000
--- a/tests/wpt/metadata/fetch/api/basic/scheme-about.any.js.ini
+++ /dev/null
@@ -1,41 +0,0 @@
-[scheme-about.any.html]
-  type: testharness
-  [Fetching about:blank (GET) is OK]
-    expected: FAIL
-
-  [Fetching about:blank (PUT) is OK]
-    expected: FAIL
-
-  [Fetching about:blank (POST) is OK]
-    expected: FAIL
-
-  [Fetching about:blank with method GET is KO]
-    expected: FAIL
-
-  [Fetching about:blank with method PUT is KO]
-    expected: FAIL
-
-  [Fetching about:blank with method POST is KO]
-    expected: FAIL
-
-
-[scheme-about.any.worker.html]
-  type: testharness
-  [Fetching about:blank (GET) is OK]
-    expected: FAIL
-
-  [Fetching about:blank (PUT) is OK]
-    expected: FAIL
-
-  [Fetching about:blank (POST) is OK]
-    expected: FAIL
-
-  [Fetching about:blank with method GET is KO]
-    expected: FAIL
-
-  [Fetching about:blank with method PUT is KO]
-    expected: FAIL
-
-  [Fetching about:blank with method POST is KO]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/workers/constructors/Worker/same-origin.html.ini b/tests/wpt/metadata/workers/constructors/Worker/same-origin.html.ini
index de990d5d1e6..40a980b618b 100644
--- a/tests/wpt/metadata/workers/constructors/Worker/same-origin.html.ini
+++ b/tests/wpt/metadata/workers/constructors/Worker/same-origin.html.ini
@@ -1,9 +1,5 @@
 [same-origin.html]
   type: testharness
-  expected: TIMEOUT
   [unsupported_scheme]
     expected: FAIL
 
-  [about_blank]
-    expected: TIMEOUT
-
diff --git a/tests/wpt/metadata/xhr/send-non-same-origin.htm.ini b/tests/wpt/metadata/xhr/send-non-same-origin.htm.ini
deleted file mode 100644
index 6e2cd942631..00000000000
--- a/tests/wpt/metadata/xhr/send-non-same-origin.htm.ini
+++ /dev/null
@@ -1,5 +0,0 @@
-[send-non-same-origin.htm]
-  type: testharness
-  [XMLHttpRequest: send() - non same-origin (about:blank)]
-    expected: FAIL
-