Auto merge of #20406 - kwonoj:feat-fetch-body-arraybuffer, r=jdm

feat(fetch): accept arraybuffer in consume_body

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Related to https://github.com/servo/servo/issues/20346.

I realized I am not sufficiently knowledgeable about codebases and have high confidence this PR is not ready to be accepted. Raising it as PR early to possibly ask some suggestions around codebases.

If this PR seems unrecoverable by code review, please feel freely close and unassign me from issue 🙏

This PR tries to implement #20346, updating `Body` idl and implements corresponding implementation in `body.rs` for `fetch`. Criteria for changes may includes

- does `run_array_buffer_data_algorithm` implementation is legit for allocating arraybuffer? (probably not)
- does `run_array_buffer_data_algorithm` implementation is acceptable for handling error, by naively returning `Error::JSFailed`?
- there are some number of wpt test started to PASS with this PR. Is this legit side effect, or something incorrect by current implementation?
- etcs, vice versa

---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #20346 (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____
- wpt test has changed in PR, need to be reviewed.

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components/script/dom/request.rs

@@ -611,6 +611,12 @@ impl RequestMethods for Request {
     fn Json(&self) -> Rc<Promise> {
         consume_body(self, BodyType::Json)
     }
+
+    #[allow(unrooted_must_root)]
+    // https://fetch.spec.whatwg.org/#dom-body-arraybuffer
+    fn ArrayBuffer(&self) -> Rc<Promise> {
+        consume_body(self, BodyType::ArrayBuffer)
+    }
 }
 
 impl BodyOperations for Request {

components/script/dom/response.rs

@@ -354,6 +354,12 @@ impl ResponseMethods for Response {
     fn Json(&self) -> Rc<Promise> {
         consume_body(self, BodyType::Json)
     }
+
+    #[allow(unrooted_must_root)]
+    // https://fetch.spec.whatwg.org/#dom-body-arraybuffer
+    fn ArrayBuffer(&self) -> Rc<Promise> {
+        consume_body(self, BodyType::ArrayBuffer)
+    }
 }
 
 fn serialize_without_fragment(url: &ServoUrl) -> &str {

components/script/dom/webidls/Body.webidl

@@ -10,7 +10,7 @@
 interface Body {
   readonly attribute boolean bodyUsed;
 
-  // [NewObject] Promise<ArrayBuffer> arrayBuffer();
+  [NewObject] Promise<ArrayBuffer> arrayBuffer();
   [NewObject] Promise<Blob> blob();
   [NewObject] Promise<FormData> formData();
   [NewObject] Promise<any> json();