Support non-ASCII headers returned by fetch (#23510)

As an example, wordpress seems to use the `X-Olaf` header set to `⛄️` which would cause `fetch` to fail.

GitOrigin-RevId: b8f82419d87882ab6e77dfd446e214af9ca602bb

crates/isolate/src/http.rs

@@ -134,9 +134,11 @@ impl HttpResponseV8 {
         // None as the HeaderName for headers with multiple values
         // (https://docs.rs/http/latest/http/header/struct.HeaderMap.html#method.into_iter)
         for (name, value) in &response.headers {
-            let value_str = value.to_str()?;
+            // Don't use `value.to_str()` since that does not support non-ASCII headers
+            let value_bytes = value.as_bytes();
+            let value_str: String = value_bytes.iter().map(|&c| c as char).collect();
             let header_name_str = name.as_str();
-            header_pairs.push((header_name_str.to_string(), value_str.to_string()));
+            header_pairs.push((header_name_str.to_string(), value_str));
         }
         // reqwest does not expose status text sent in HTTP response, so we derive it
         // from status code.

npm-packages/udf-runtime/src/23_response.ts

@@ -271,7 +271,7 @@ export class Response {
       statusText: this.statusText,
       url: this._url,
     };
-    return `Request ${inspect(properties)}`;
+    return `Response ${inspect(properties)}`;
   }
 
   // ---------------------------------------------------------------

npm-packages/udf-tests/convex/fetch.ts

@@ -111,6 +111,7 @@ export default action(async () => {
     fetchResponseStreamIsLockedWhileReading,
     fetchResponseStreamIsLockedWhileReadingBlob,
     fetchForbidden,
+    fetchOlaf,
   });
 });
 
@@ -1745,3 +1746,12 @@ export const fetchUnendingRequest = action(async () => {
   await response.text();
   throw new Error(`fetch should not complete`);
 });
+
+// Regression test for https://webtechsurvey.com/response-header/x-olaf
+async function fetchOlaf() {
+  const response = await fetch("http://localhost:4545/echo_server", {
+    method: "POST",
+    headers: { "X-Olaf": "⛄" },
+  });
+  assert.strictEqual(response.headers.get("X-Olaf"), "â\x9B\x84");
+}