http: reuse existing headers array for raw values

PR-URL: #6533
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

lib/_http_incoming.js

@@ -103,21 +103,17 @@ IncomingMessage.prototype.destroy = function destroy(error) {
 IncomingMessage.prototype._addHeaderLines = _addHeaderLines;
 function _addHeaderLines(headers, n) {
   if (headers && headers.length) {
-    var raw, dest;
+    var dest;
     if (this.complete) {
-      raw = this.rawTrailers;
+      this.rawTrailers = headers;
       dest = this.trailers;
     } else {
-      raw = this.rawHeaders;
+      this.rawHeaders = headers;
       dest = this.headers;
     }
 
     for (var i = 0; i < n; i += 2) {
-      var k = headers[i];
-      var v = headers[i + 1];
-      raw.push(k);
-      raw.push(v);
-      this._addHeaderLine(k, v, dest);
+      this._addHeaderLine(headers[i], headers[i + 1], dest);
     }
   }
 }