Auto merge of #12998 - jeenalee:iterable-headers, r=jdm

Implement iterable for headers

<!-- Please describe your changes on the following line: -->
These patches make Headers iterable based on #12819.

The expected wpt results are updated as well.

---
<!-- 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
- [ ] These changes fix #__ (github issue number if applicable).

<!-- Either: -->
- [x] There are tests for these changes OR
- [ ] These changes do not require tests because web platform tests for Headers already exist. Expected test results are updated with this PR.

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

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4 files changed, 39 insertions, 18 deletions

diff --git a/components/script/dom/headers.rs b/components/script/dom/headers.rs
index 6fa4e0249c8..7b45956c039 100644
--- a/components/script/dom/headers.rs
+++ b/components/script/dom/headers.rs
@@ -5,9 +5,11 @@
 use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::HeadersBinding;
 use dom::bindings::codegen::Bindings::HeadersBinding::HeadersMethods;
+use dom::bindings::codegen::Bindings::HeadersBinding::HeadersWrap;
 use dom::bindings::codegen::UnionTypes::HeadersOrByteStringSequenceSequence;
 use dom::bindings::error::{Error, ErrorResult, Fallible};
 use dom::bindings::global::GlobalRef;
+use dom::bindings::iterable::Iterable;
 use dom::bindings::js::Root;
 use dom::bindings::reflector::{Reflector, reflect_dom_object};
 use dom::bindings::str::{ByteString, is_token};
@@ -45,7 +47,7 @@ impl Headers {
     }
 
     pub fn new(global: GlobalRef) -> Root<Headers> {
-        reflect_dom_object(box Headers::new_inherited(), global, HeadersBinding::Wrap)
+        reflect_dom_object(box Headers::new_inherited(), global, HeadersWrap)
     }
 
     // https://fetch.spec.whatwg.org/#dom-headers
@@ -223,6 +225,41 @@ impl Headers {
     pub fn extract_mime_type(&self) -> Vec<u8> {
         self.header_list.borrow().get_raw("content-type").map_or(vec![], |v| v[0].clone())
     }
+
+    pub fn sort_header_list(&self) -> Vec<(String, String)> {
+        let borrowed_header_list = self.header_list.borrow();
+        let headers_iter = borrowed_header_list.iter();
+        let mut header_vec = vec![];
+        for header in headers_iter {
+            let name = header.name().to_string();
+            let value = header.value_string();
+            let name_value = (name, value);
+            header_vec.push(name_value);
+        }
+        header_vec.sort();
+        header_vec
+    }
+}
+
+impl Iterable for Headers {
+    type Key = ByteString;
+    type Value = ByteString;
+
+    fn get_iterable_length(&self) -> u32 {
+        self.header_list.borrow().iter().count() as u32
+    }
+
+    fn get_value_at_index(&self, n: u32) -> ByteString {
+        let sorted_header_vec = self.sort_header_list();
+        let value = sorted_header_vec[n as usize].1.clone();
+        ByteString::new(value.into_bytes().to_vec())
+    }
+
+    fn get_key_at_index(&self, n: u32) -> ByteString {
+        let sorted_header_vec = self.sort_header_list();
+        let key = sorted_header_vec[n as usize].0.clone();
+        ByteString::new(key.into_bytes().to_vec())
+    }
 }
 
 fn is_cors_safelisted_request_content_type(value: &[u8]) -> bool {
diff --git a/components/script/dom/webidls/Headers.webidl b/components/script/dom/webidls/Headers.webidl
index 6696bf64731..ee3d4b2fe94 100644
--- a/components/script/dom/webidls/Headers.webidl
+++ b/components/script/dom/webidls/Headers.webidl
@@ -20,5 +20,5 @@ interface Headers {
   boolean has(ByteString name);
   [Throws]
   void set(ByteString name, ByteString value);
-  // iterable<ByteString, ByteString>; // TODO see issue #12628
+  iterable<ByteString, ByteString>;
 };
diff --git a/tests/wpt/metadata/fetch/api/headers/headers-errors.html.ini b/tests/wpt/metadata/fetch/api/headers/headers-errors.html.ini
deleted file mode 100644
index 3941ca87bcf..00000000000
--- a/tests/wpt/metadata/fetch/api/headers/headers-errors.html.ini
+++ /dev/null
@@ -1,5 +0,0 @@
-[headers-errors.html]
-  type: testharness
-  [Headers forEach loop should stop if callback is throwing exception]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/fetch/api/headers/headers-structure.html.ini b/tests/wpt/metadata/fetch/api/headers/headers-structure.html.ini
deleted file mode 100644
index e2cbf6a708e..00000000000
--- a/tests/wpt/metadata/fetch/api/headers/headers-structure.html.ini
+++ /dev/null
@@ -1,11 +0,0 @@
-[headers-structure.html]
-  type: testharness
-  [Headers has entries method]
-    expected: FAIL
-
-  [Headers has keys method]
-    expected: FAIL
-
-  [Headers has values method]
-    expected: FAIL
-