perf: set isLowerCase param on all calls of HeadersList.append

lib/web/cookies/index.js

@@ -102,7 +102,7 @@ function setCookie (headers, cookie) {
   const str = stringify(cookie)
 
   if (str) {
-    headers.append('Set-Cookie', str)
+    headers.append('set-cookie', str, true)
   }
 }
 

lib/web/fetch/index.js

@@ -1460,7 +1460,7 @@ async function httpNetworkOrCacheFetch (
   //    user agents should append `User-Agent`/default `User-Agent` value to
   //    httpRequest’s header list.
   if (!httpRequest.headersList.contains('user-agent', true)) {
-    httpRequest.headersList.append('user-agent', defaultUserAgent)
+    httpRequest.headersList.append('user-agent', defaultUserAgent, true)
   }
 
   //    15. If httpRequest’s cache mode is "default" and httpRequest’s header

lib/web/fetch/request.js

@@ -520,7 +520,7 @@ class Request {
       // not contain `Content-Type`, then append `Content-Type`/Content-Type to
       // this’s headers.
       if (contentType && !getHeadersList(this[kHeaders]).contains('content-type', true)) {
-        this[kHeaders].append('content-type', contentType)
+        this[kHeaders].append('content-type', contentType, true)
       }
     }
 

lib/web/websocket/connection.js

@@ -22,7 +22,7 @@ try {
  * @param {URL} url
  * @param {string|string[]} protocols
  * @param {import('./websocket').Handler} handler
- * @param {Partial<import('../../types/websocket').WebSocketInit>} options
+ * @param {Partial<import('../../../types/websocket').WebSocketInit>} options
  */
 function establishWebSocketConnection (url, protocols, client, handler, options) {
   // 1. Let requestURL be a copy of url, with its scheme set to "http", if url’s
@@ -65,17 +65,17 @@ function establishWebSocketConnection (url, protocols, client, handler, options)
 
   // 6. Append (`Sec-WebSocket-Key`, keyValue) to request’s
   //    header list.
-  request.headersList.append('sec-websocket-key', keyValue)
+  request.headersList.append('sec-websocket-key', keyValue, true)
 
   // 7. Append (`Sec-WebSocket-Version`, `13`) to request’s
   //    header list.
-  request.headersList.append('sec-websocket-version', '13')
+  request.headersList.append('sec-websocket-version', '13', true)
 
   // 8. For each protocol in protocols, combine
   //    (`Sec-WebSocket-Protocol`, protocol) in request’s header
   //    list.
   for (const protocol of protocols) {
-    request.headersList.append('sec-websocket-protocol', protocol)
+    request.headersList.append('sec-websocket-protocol', protocol, true)
   }
 
   // 9. Let permessageDeflate be a user-agent defined
@@ -85,7 +85,7 @@ function establishWebSocketConnection (url, protocols, client, handler, options)
 
   // 10. Append (`Sec-WebSocket-Extensions`, permessageDeflate) to
   //     request’s header list.
-  request.headersList.append('sec-websocket-extensions', permessageDeflate)
+  request.headersList.append('sec-websocket-extensions', permessageDeflate, true)
 
   // 11. Fetch request with useParallelQueue set to true, and
   //     processResponse given response being these steps: